expectorate (v.) Look up expectorate at Dictionary.com
c. 1600, "to clear out the chest or lungs," a literal use of Latin expectoratus, past participle of expectorare, which in classical use was figurative, "scorn, expel from the mind," literally "drive from the breast, make a clean breast," from ex- "out" (see ex-) + pectus (genitive pectoris) "breast" (see pectoral (adj.)). Its use as a euphemism for "spit" is recorded by 1827. The classical Latin figurative sense appears in English 17c. but is now obsolete. Related: Expectorated; expectorating.
expectoration (n.) Look up expectoration at Dictionary.com
1670s, noun of action from expectorate.
expediate (v.) Look up expediate at Dictionary.com
a 17c. error for expedite that has gotten into the dictionaries.
expedience (n.) Look up expedience at Dictionary.com
mid-15c., "advantage, benefit," from Old French expedience, from Late Latin expedientia, from expedientem (see expedient). From "that which is expedient," the sense tends toward "utilitarian wisdom." Meaning "quality of being expedient" is from 1610s. Related: Expediency (1610s).
expedient (adj.) Look up expedient at Dictionary.com
late 14c., "advantageous, fit, proper to a purpose," from Old French expedient "useful, beneficial" (14c.) or directly from Latin expedientem (nominative expediens) "beneficial," present participle of expedire "make fit or ready, prepare" (see expedite). The noun meaning "a device adopted in an exigency, that which serves to advance a desired result" is from 1650s. Related: Expediential; expedientially (both 19c.).
Expedient, contrivance, and device indicate artificial means of escape from difficulty or embarrassment; resource indicates natural means or something possessed; resort and shift may indicate either. [Century Dictionary]
expediently (adv.) Look up expediently at Dictionary.com
late 14c., from expedient (adj.) + -ly (2).
expedite (v.) Look up expedite at Dictionary.com
c. 1500 (implied in past participle expedit "accomplished"), from Latin expeditus, past participle of expedire "extricate, disengage, liberate; procure, make ready, put in order, make fit, prepare; explain, make clear," literally "free the feet from fetters," hence to liberate from difficulties, from ex- "out" (see ex-) + *pedis "fetter, chain for the feet," related to pes (genitive pedis) "foot," from PIE root *ped- (1) "a foot" (see foot (n.)). Compare Greek pede "fetter." Related: Expedited; expediting.
expedition (n.) Look up expedition at Dictionary.com
early 15c., "military campaign; the act of rapidly setting forth," from Old French expedicion "an expediting, implementation; expedition, mission" (13c.) and directly from Latin expeditionem (nominative expeditio) "an enterprise against an enemy, a military campaign," noun of action from past participle stem of expedire "make ready, prepare" (see expedite). Meaning "journey for some purpose" is from 1590s. Sense by 1690s also included the body of persons on such a journey.
expeditionary (adj.) Look up expeditionary at Dictionary.com
1803, from expedition + -ary.
expeditious (adj.) Look up expeditious at Dictionary.com
late 15c., expedycius "useful, fitting," from Latin expeditus "disengaged, ready, convenient, prompt; unfettered, unencumbered," past participle of expedire (see expedite). Meaning "speedy, speedily accomplished" is from 1590s. Related: Expeditiously; expeditiousness.
expel (v.) Look up expel at Dictionary.com
late 14c., "cast out," from Latin expellere "drive out, drive away," from ex- "out" (see ex-) + pellere "to drive" (see pulse (n.1)). Specific meaning "to eject from a school" is first recorded 1640s. Related: Expelled; expelling.
expellee (n.) Look up expellee at Dictionary.com
1888, from expel + -ee.
expend (v.) Look up expend at Dictionary.com
early 15c., from Latin expendere "pay out, weigh out money," from ex- "out" (see ex-) + pendere "to pay, weigh" (see pendant). Related: Expended; expending.
expendable (adj.) Look up expendable at Dictionary.com
1805, from expend + -able.
expenditure (n.) Look up expenditure at Dictionary.com
1769, "act of expending," from Medieval Latin expenditus, irregular past participle of Latin expendere "to weigh out; to pay out" (see expend) + -ure. Meaning "that which is expended" is from 1791. Related: Expenditures.
expense (n.) Look up expense at Dictionary.com
also formerly expence, late 14c., "action of spending or giving away, a laying out or expending," also "funds provided for expenses, expense money; damage or loss from any cause," from Anglo-French expense, Old French espense "money provided for expenses," from Late Latin expensa "disbursement, outlay, expense," noun use of neuter plural past participle of Latin expendere "to weigh out money, to pay down" (see expend).

Latin spensa also yielded Medieval Latin spe(n)sa, the sense of which specialized to "outlay for provisions," then "provisions, food" before it was borrowed into Old High German as spisa and became the root of German Speise "food," now mostly meaning prepared food, and speisen "to eat." Expense account is from 1872.
expense (v.) Look up expense at Dictionary.com
1909, from expense (n.). Related: Expensed; expensing.
expenses (n.) Look up expenses at Dictionary.com
"charges incurred in the discharge of duty," late 14c. See expense (n.).
expensive (adj.) Look up expensive at Dictionary.com
1620s, "given to profuse expenditure," from expense (n.) + -ive. Meaning "costly, requiring profuse expenditure" is from 1630s. Earlier was expenseful (c. 1600). Expenseless was in use mid-17c.-18c., but there seems now nothing notable to which it applies, and the dictionaries label it "obsolete." Related: Expensively; expensiveness.
experience (n.) Look up experience at Dictionary.com
late 14c., "observation as the source of knowledge; actual observation; an event which has affected one," from Old French esperience "experiment, proof, experience" (13c.), from Latin experientia "a trial, proof, experiment; knowledge gained by repeated trials," from experientem (nominative experiens) "experienced, enterprising, active, industrious," present participle of experiri "to try, test," from ex- "out of" (see ex-) + peritus "experienced, tested," from PIE root *per- (3) "to lead, pass over" (see peril). Meaning "state of having done something and gotten handy at it" is from late 15c.
experience (v.) Look up experience at Dictionary.com
1530s, "to test, try, learn by practical trial or proof;" see experience (n.). Sense of "feel, undergo" first recorded 1580s. Related: Experienced; experiences; experiencing.
experienced (adj.) Look up experienced at Dictionary.com
"having experience, taught by practice, skillful through doing," 1570s, past participle adjective from experience (v.).
experiential (adj.) Look up experiential at Dictionary.com
1640s (implied in experientially), from Latin experientia "knowledge gained by testing or trials" (see experience (n.)) + -al (1).
experiment (n.) Look up experiment at Dictionary.com
mid-14c., "action of observing or testing; an observation, test, or trial;" also "piece of evidence or empirical proof; feat of magic or sorcery," from Old French esperment "practical knowledge, cunning; enchantment, magic spell; trial, proof, example; lesson, sign, indication," from Latin experimentum "a trial, test, proof, experiment," noun of action from experiri "to test, try" (see experience (n.)).
experiment (v.) Look up experiment at Dictionary.com
late 15c., from experiment (n.). Intransitive sense by 1787. Related: Experimented; experimenting.
experimental (adj.) Look up experimental at Dictionary.com
mid 15c., "having experience," from experiment (n.) + -al (1). Meaning "based on experiment" is from 1560s. Meaning "for the sake of experiment" is from 1792.
experimentation (n.) Look up experimentation at Dictionary.com
1670s, noun of action from experiment (v.).
expert (adj.) Look up expert at Dictionary.com
late 14c., "having had experience; skillful," from Old French expert, espert "experienced, practiced, skilled" and directly from Latin expertus (contracted from *experitus), "tried, proved, known by experience," past participle of experiri "to try, test" (see experience). The adjective tends to be accented on the second syllable, the noun on the first. Related: Expertly; expertness.
expert (n.) Look up expert at Dictionary.com
early 15c., "person wise through experience," from expert (adj.). The word reappeared 1825 in the legal sense, "person who, by virtue of special acquired knowledge or experience on a subject, presumably not within the knowledge of men generally, may testify in a court of justice to matters of opinion thereon, as distinguished from ordinary witnesses, who can in general testify only to facts" [Century Dictionary].
expertise (n.) Look up expertise at Dictionary.com
"quality or state of being an expert," 1868, from French expertise (16c.) "expert appraisal, expert's report," from expert (see expert). Earlier and more English was expertness (c. 1600).
experto crede Look up experto crede at Dictionary.com
Latin, "take it from one who knows" ("Aeneid," xi.283); dative singular of expertus (see expert (adj.)) + imperative singular of credere (see credo).
expiate (v.) Look up expiate at Dictionary.com
c. 1600 (OED 2nd ed. print entry has a typographical error in the earliest date), from Latin expiatus, past participle of expiare "to make amends, atone for" (see expiation). Related: Expiable (1560s); expiated; expiating.
expiation (n.) Look up expiation at Dictionary.com
early 15c., via Middle French expiation or directly from Latin expiationem (nominative expiatio) "satisfaction, atonement," noun of action from past participle stem of expiare "make amends for, atone for; purge by sacrifice, make good," from ex- "completely" (see ex-) + piare "propitiate, appease," from pius "faithful, loyal, devout" (see pious).
The sacrifice of expiation is that which tendeth to appease the wrath of God. [Thomas Norton, translation of Calvin's "Institutes of Christian Religion," 1561]
expiatory (adj.) Look up expiatory at Dictionary.com
1540s, from Late Latin expiatorius, from expiat-, past participle stem of Latin expiare "make amends" (see expiation).
expiration (n.) Look up expiration at Dictionary.com
early 15c., "vapor, breath," from Middle French expiration, from Latin expirationem/exspirationem (nominative expiratio/exspiratio) "a breathing out, exhalation," noun of action from past participle stem of expirare/exspirare "breathe out; breathe one's last" (see expire). Meaning "termination, end, close" is from 1560s.
expire (v.) Look up expire at Dictionary.com
c. 1400, "to die," from Old French expirer "expire, elapse" (12c.), from Latin expirare/exspirare "breathe out, blow out, exhale; breathe one's last, die," hence, figuratively, "expire, come to an end, cease," from ex- "out" (see ex-) + spirare "to breathe" (see spirit (n.)). "Die" is the older sense in English; that of "breathe out" is first attested 1580s. Of laws, patents, treaties, etc., mid-15c. In 17c. also transitive. Related: Expired; expiring.
expiry (n.) Look up expiry at Dictionary.com
"close, termination," 1752, from expire + -y (4). Meaning "dying, death" is from 1790.
explain (v.) Look up explain at Dictionary.com
early 15c., from Latin explanare "to explain, make clear, make plain" (see explanation). Originally explane, spelling altered by influence of plain. Also see plane (v.2). In 17c., occasionally used more literally, of the unfolding of material things: Evelyn has buds that "explain into leaves" ["Sylva, or, A discourse of forest-trees, and the propagation of timber in His Majesties dominions," 1664]. Related: Explained; explaining; explains. To explain (something) away is from 1709.
explainable (adj.) Look up explainable at Dictionary.com
c. 1600, from explain + -able.
explanation (n.) Look up explanation at Dictionary.com
late 14c., from Latin explanationem (nominative explanatio) "an explanation, interpretation," noun of action from past participle stem of explanare "to make plain or clear, explain," literally "make level, flatten," from ex- "out" (see ex-) + planus "flat" (see plane (n.1)).
explanatory (adj.) Look up explanatory at Dictionary.com
1610s, from or modeled on Late Latin explanatorius "having to do with an explanation," from Latin explanat-, past participle stem of explanare "make plain or clear" (see explanation).
expletive (n.) Look up expletive at Dictionary.com
1610s, "a word or phrase serving to fill out a sentence or metrical line," from Middle French explétif (15c.) and directly from Late Latin expletivus "serving to fill out," from explet-, past participle stem of Latin explere "fill out, fill up, glut," from ex- "out" (see ex-) + plere "to fill" (see pleio-).

Sense of "an exclamation," especially "a curse word, an oath," first recorded 1815 in Sir Walter Scott, popularized by edited transcripts of Watergate tapes (mid-1970s), in which expletive deleted replaced President Nixon's salty expressions. As an adjective, from 1660s.
expletive (adj.) Look up expletive at Dictionary.com
mid-15c., in grammar, "correlative," from Latin expletivus "serving to fill out" (see expletive (n.)).
explicable (adj.) Look up explicable at Dictionary.com
1550s, from or modeled on Latin explicabilis "capable of being unraveled, that may be explained," from explicare "unfold; explain" (see explicit). Middle English had a verb expliken "explain, interpret" (mid-15c.).
explicate (v.) Look up explicate at Dictionary.com
"give a detailed account of," 1530s, from Latin explicatus, past participle of explicare "unfold, unravel, explain" (see explicit). Related: Explicated; explicating.
explication (n.) Look up explication at Dictionary.com
1520s, from Middle French explication, from Latin explicationem (nominative explicatio), noun of action from past participle stem of explicare "unfold; explain" (see explicit).
explicative (adj.) Look up explicative at Dictionary.com
1640s, "having the function of explaining," from Latin explicativus, from explicat-, past participle stem of explicare "unfold; explain" (see explicit). As a noun, from 1775.
explicit (adj.) Look up explicit at Dictionary.com
1610s, "open to the understanding, not obscure or ambiguous," from French explicite, from Latin explicitus "unobstructed," variant past participle of explicare "unfold, unravel, explain," from ex- "out" (see ex-) + plicare "to fold" (see ply (v.1)). As a euphemism for "pornographic" it dates from 1971. Related: Explicitness. "Explicitus" was written at the end of medieval books, originally short for explicitus est liber "the book is unrolled."
explicitly (adv.) Look up explicitly at Dictionary.com
1630s, from explicit + -ly (2). Opposed to implicitly.
explode (v.) Look up explode at Dictionary.com
1530s (transitive), "to reject with scorn," from Latin explodere "drive out or off by clapping, hiss off, hoot off," originally theatrical, "to drive an actor off the stage by making noise," hence "drive out, reject, destroy the repute of" (a sense surviving in an exploded theory), from ex- "out" (see ex-) + plaudere "to clap the hands, applaud," which is of uncertain origin. Athenian audiences were highly demonstrative. clapping and shouting approval, stamping, hissing, and hooting for disapproval. The Romans seem to have done likewise.
At the close of the performance of a comedy in the Roman theatre one of the actors dismissed the audience, with a request for their approbation, the expression being usually plaudite, vos plaudite, or vos valete et plaudite. [William Smith, "A First Latin Reading Book," 1890]
English used it to mean "drive out with violence and sudden noise" (1650s), later "cause to burst suddenly and noisily" (1794). Intransitive sense of "go off with a loud noise" is from 1790, American English; figurative sense of "to burst with destructive force" is by 1882; that of "burst into sudden activity" is from 1817; of population by 1959. Related: Exploded; exploding.