en route Look up en route at Dictionary.com
1779, French, literally "on the way."
en suite Look up en suite at Dictionary.com
French, literally "as part of a series or set."
en- (1) Look up en- at Dictionary.com
word-forming element meaning "in, into," from French and Old French en-, from Latin in- "in, into" (see in- (2)). Typically assimilated to -p-, -b-, -m-, -l-, and -r-.

Also used with native elements to form verbs from nouns and adjectives, "put in or on" (encircle), also "cause to be, make" (endear), and used as an intensive (enclose). Spelling variants in French that were brought over into Middle English account for parallels such as assure/ensure/insure.
en- (2) Look up en- at Dictionary.com
word-forming element meaning "near, at in, on, within," from Greek en "in," cognate with Latin in (see in), and with en- (1). Typically assimilated to -p-, -b-, -m-, -l-, and -r-.
enable (v.) Look up enable at Dictionary.com
early 15c., "to make fit;" mid-15c., "to make able to," from en- (1) "make, put in" + able. Related: Enabled; enabling.
enabler (n.) Look up enabler at Dictionary.com
1610s, agent noun from enable.
enact (v.) Look up enact at Dictionary.com
early 15c., from en- (1) "make, put in" + act (v.). Related: Enacted; enacting.
enactment (n.) Look up enactment at Dictionary.com
1817, from enact + -ment.
enamel (v.) Look up enamel at Dictionary.com
early 14c., from Anglo-French enamailler (early 14c.), from en- "in" (see en- (1)) + amailler "to enamel," variant of Old French esmailler, from esmal "enamel," from Frankish *smalt, from Proto-Germanic *smaltjan "to smelt" (see smelt (v.)). Related: Enameled; enameling.
enamel (n.) Look up enamel at Dictionary.com
early 15c., from enamel (v.).
enamor (v.) Look up enamor at Dictionary.com
c.1300, from Old French enamorer "to fall in love with; to inspire love" (12c., Modern French enamourer), from en-, causative prefix (see en- (1)), + amour "love," from amare "to love" (see Amy). An equivalent formation to Provençal, Spanish, Portuguese enamorar, Italian innamorare.
enamored (adj.) Look up enamored at Dictionary.com
1630s, past participle adjective from enamor.
enamour (v.) Look up enamour at Dictionary.com
chiefly British English form of enamor; for spelling, see -or. Related: Enamoured.
encamp (v.) Look up encamp at Dictionary.com
1560s, from en- (1) "make, put in" + camp (v.). Related: Encamped; encamping.
encampment (n.) Look up encampment at Dictionary.com
1590s, from encamp + -ment.
encapsulate (v.) Look up encapsulate at Dictionary.com
1842 (implied in encapsulated), from en- (1) "make, put in" + capsule + -ate (2)). Related: Encapsulating.
encapsulation (n.) Look up encapsulation at Dictionary.com
1859, noun of action from encapsulate.
encase (v.) Look up encase at Dictionary.com
1630s, from en- (1) "make, put in" + case (n.2). Related: Encased; encasing.
encaustic Look up encaustic at Dictionary.com
c.1600 (n.); 1650s (adj.), from Greek enkaustikos, from enkaiein "to burn in" from en (see en- (2)) + kaiein "to burn" (see caustic).
enceinte (adj.) Look up enceinte at Dictionary.com
c.1600, insente, from French enceinte "pregnant" (12c.), from Late Latin incincta (source of Italian incinta), usually explained as "ungirt," from Latin in-, privative prefix (see in- (1)), + cincta, fem. of cinctus, past participle of cingere "to gird" (see cinch). Modern form is 18c., perhaps a reborrowing from French.
encephalitis (n.) Look up encephalitis at Dictionary.com
1843, from medical Latin encephalon (from Greek enkephalos "brain," literally "within the head," from en "in" + kephale "head;" see cephalo-) + -itis.
enchant (v.) Look up enchant at Dictionary.com
late 14c., literal and figurative, from Old French enchanter "bewitch, charm, cast a spell" (12c.), from Latin incantare (see enchantment). Or perhaps a back-formation from enchantment. Related: Enchanting; enchantingly. Enchanted in weakened sense of "delighted" is from 1590s.
enchanter (n.) Look up enchanter at Dictionary.com
late 13c., agent noun from enchant or from Old French enchanteor.
enchantment (n.) Look up enchantment at Dictionary.com
late 13c., from Old French encantement, from enchanter "bewitch, charm," from Latin incantare, literally "enchant, cast a (magic) spell upon," from in- "upon, into" (see in- (2)) + cantare "to sing" (see chant (v.)). Figurative sense of "alluring" is from 1670s. Compare Old English galdor "song," also "spell, enchantment," from galan "to sing," source of the second element in nightingale.
enchantress (n.) Look up enchantress at Dictionary.com
late 14c., "witch," from enchanter + -ess. Meaning "charming woman" is from 1713.
enchilada (n.) Look up enchilada at Dictionary.com
1887, American English, from Mexican Spanish enchilada, fem. past participle of enchilar "season with chili," from en- "in" + chile "chili" (see chili).
enchiridion (n.) Look up enchiridion at Dictionary.com
1540s, "a handbook," from Late Latin, from Greek enkheiridion, neuter of enkheiridios "that which is held in the hand," from en "in" (see en- (2)) + kheir "hand" (see chiro-) + diminutive suffix -idion.
encircle (v.) Look up encircle at Dictionary.com
c.1400, from en- (1) "make, put in" + circle. Related: Encircled; encircling; encirclement.
enclave (n.) Look up enclave at Dictionary.com
1868, from French enclave, from Old French enclaver "enclose, comprise, include" (13c.), from Late Latin inclavare "shut in, lock up," from Latin in- "in" (see in- (2)) + clavis "key" (see slot (n.2)). Enclaved "surrounded by land owned by another" is attested in English from mid-15c., from Middle French enclaver.
enclitic Look up enclitic at Dictionary.com
1650s (adj.); 1660s (n.), from Late Latin encliticus, from Greek enklitikos "throwing its accent back," literally "leaning on," from verbal adjectival stem of enklinein "to bend, lean on," from en (see en- (2)) + klinein "to lean" (see lean (v.)).
enclose (v.) Look up enclose at Dictionary.com
early 14c., from en- (1) + close, and partially from Old French enclos, past participle of enclore.

Specific sense of "to fence in waste or common ground" for the purpose of cultivation or to give it to private owners, is from c.1500. Meaning "place a document with a letter for transmission" is from 1707. Related: Enclosed; enclosing.
enclosure (n.) Look up enclosure at Dictionary.com
mid-15c., "action of enclosing," from enclose + -ure. Meaning "that which is enclosed" is from 1550s.
encode (v.) Look up encode at Dictionary.com
1919, from en- (1) "make, put in" + code. Computing sense is from 1955, usually shortened colloquially to code. Related: Encoded; encoding.
encomiast (n.) Look up encomiast at Dictionary.com
c.1600, from Greek enkomiastes "one who praises," from enkomiazein, from enkomion (see encomium). Related: Encomiastic (1590s).
encomienda (n.) Look up encomienda at Dictionary.com
1810, from Spanish, "commission," from encomendar "to commit, charge." Estate granted to a Spaniard in America with powers to tax the Indians.
encomium (n.) Look up encomium at Dictionary.com
1580s, from Late Latin encomium, from Greek enkomion (epos) "laudatory (ode), eulogy," from en "in" (see en- (2)) + komos "banquet, procession, merrymaking" (see comedy).
encompass (v.) Look up encompass at Dictionary.com
1550s, from en- (1) "make, put in" + compass. Related: Encompassed; encompasses; encompassing.
encore (interj.) Look up encore at Dictionary.com
1712, from French encore "still, yet, again" (12c.), generally explained as being from Vulgar Latin phrase *hinc ad horam "from then to this hour" (Italian ancora "again, still, yet" is said to be a French loan-word).
Whenever any Gentlemen are particularly pleased with a Song, at their crying out Encore ... the Performer is so obliging as to sing it over again. [Steele, "Spectator" No. 314, 1712]

There appears to be no evidence that either the Fr. or It. word was ever similarly used in its native country. The corresponding word both in Fr. and It. is bis; in It. da capo was formerly used. [OED]
As a noun, from 1763; as a verb, from 1748.
encounter (n.) Look up encounter at Dictionary.com
c.1300, "meeting of adversaries, confrontation," from Old French encontre "meeting; fight; opportunity," noun use of preposition/adverb encontre "against, counter to" from Late Latin incontra "in front of," from Latin in- "in" (see in- (2)) + contra "against" (see contra). Modern use of the word in psychology is from 1967, from the work of U.S. psychologist Carl Rogers (1902-1987). Encounter group attested from 1967.
encounter (v.) Look up encounter at Dictionary.com
c.1300, "to meet as an adversary," from Old French encontrer "confront," from encontre (see encounter (n.). Weakened sense of "casually meet" first recorded in English early 16c. Related: Encountered; encountering.
encourage (v.) Look up encourage at Dictionary.com
early 15c., from Old French encoragier "make strong, hearten," from en- "make, put in" (see en- (1)) + corage (see courage). Related: Encouraged; encouraging.
encouragement (n.) Look up encouragement at Dictionary.com
1560s, from encourage + -ment, or from Middle French encoragement.
As a general rule, Providence seldom vouchsafes to mortals any more than just that degree of encouragement which suffices to keep them at a reasonably full exertion of their powers. [Hawthorne, "House of Seven Gables"]
encroach (v.) Look up encroach at Dictionary.com
early 14c., "acquire, get," from Old French encrochier "seize, fasten on, hang on (to), cling (to); hang up, suspend," literally "to catch with a hook," from en- "in" (see en- (1)) + croc "hook," from Old Norse krokr "hook" (see crook). Meaning "seize wrongfully" is from c.1400. Sense of "trespass" is first recorded 1530s. Related: Encroached; encroaches; encroaching.
encroachment (n.) Look up encroachment at Dictionary.com
1520s, from encroach + -ment. In Anglo-French from mid-15c.
encrust (v.) Look up encrust at Dictionary.com
1640s, from French incruster, from Latin incrustare "to cover with crust," from in- (see in- (2)) + crusta (see crust). Related: Encrusted; encrusting.
encrypt (v.) Look up encrypt at Dictionary.com
1975 in computer sense, from en- (1) + crypt (see crypto-). Related: Encrypted; encrypting; encryption.
enculturation (n.) Look up enculturation at Dictionary.com
1948 (Herskovits), from en- (1) + culturation (compare acculturation).
encumber (v.) Look up encumber at Dictionary.com
early 14c., "burden, vex, inconvenience," from Old French encombrer "to block up, hinder, thwart," from Late Latin incombrare, from in- "in" (see in- (2)) + combrus "barricade, obstacle," probably from Latin cumulus "heap." Meaning "hinder, hamper" is attested in English from late 14c. Related: Encumbered; encumbering.
encumbrance (n.) Look up encumbrance at Dictionary.com
early 14c., from Old French encombrance, from encombrer (see encumber).
encyclical (adj.) Look up encyclical at Dictionary.com
in reference to a letter sent by the Pope to all the bishops, 1640s, from Late Latin encyclicus, from Latin encyclius, from Greek enkyklios "in a circle, circular" (see encyclopedia). As a noun, from 1837.