donor (n.) Look up donor at Dictionary.com
mid-15c., from Anglo-French donour, Old French doneur (Modern French donneur), from Latin donatorem (nominative donator) "giver, donor," agent noun from past participle stem of donare "give as a gift" (see donation). Of blood, from 1910; of organs or tissues, from 1918.
Donovan Look up Donovan at Dictionary.com
from Irish Donndubhan "dark brown."
donut (n.) Look up donut at Dictionary.com
see doughnut. It turns up as an alternate spelling in U.S. as early as 1870 ("Josh Billings"), common from c.1920 in names of bakeries. Halliwell ("Dictionary of Archaic and Provincial Words," 1847) has donnut "a pancake made of dough instead of batter," which Bartlett (1848) writes "is no doubt the same word" as the American one.
doo-wop Look up doo-wop at Dictionary.com
1958, from the nonsense harmony phrases sung under the vocal lead (this one attested from mid-1950s).
doodad (n.) Look up doodad at Dictionary.com
"unnamed thing," 1905, chiefly U.S., a made-up word (compare doohickey).
doodah (n.) Look up doodah at Dictionary.com
"excitement," 1915, from refrain of the minstrel song "Camptown Races."
doodle (v.) Look up doodle at Dictionary.com
"scrawl aimlessly," 1935, from dialectal doodle, dudle "fritter away time, trifle," or associated with dawdle. It was a noun meaning "simple fellow" from 1620s.
LONGFELLOW: That's a name we made up back home for people who make foolish designs on paper when they're thinking. It's called doodling. Almost everybody's a doodler. Did you ever see a scratch pad in a telephone booth? People draw the most idiotic pictures when they're thinking. Dr. Von Holler, here, could probably think up a long name for it, because he doodles all the time. ["Mr. Deeds Goes to Town," screenplay by Robert Riskin, 1936; based on "Opera Hat," serialized in "American Magazine" beginning May 1935, by Clarence Aldington Kelland]
Related: Doodled; Doodling.
Doodle Sack. A bagpipe. Dutch. -- Also the private parts of a woman. ["Classical Dictionary of the Vulgar Tongue," 1796]
doodle-bug (n.) Look up doodle-bug at Dictionary.com
type of beetle or larvae, c.1866, Southern U.S. dialect; see doodle + bug (n.). The same word was applied 1944 in R.A.F. slang to German V-model flying bombs.
doofus (n.) Look up doofus at Dictionary.com
student slang, "dolt, idiot, nerd," by 1960s. "Dictionary of American Slang" says "probably related to doo-doo and goofus."
doohickey (n.) Look up doohickey at Dictionary.com
also doohicky, a name for something one doesn't know the name of, 1914, American English, arbitrary formation.
doolally (adj.) Look up doolally at Dictionary.com
"insane, eccentric," British slang, by 1917 in the armed services and in full doolally tap (with Urdu word for "fever"), from Deolali, near Bombay, India, which was a military camp (established 1861) with a large barracks and a chief staging point for British troops on their way to or from India; the reference is to men whose enlistments had expired who waited there impatiently for transport home.
doom (n.) Look up doom at Dictionary.com
Old English dom "law, judgment, condemnation," from Proto-Germanic *domaz (cognates: Old Saxon and Old Frisian dom, Old Norse domr, Old High German tuom, Gothic doms "judgment, decree"), from PIE root *dhe- (cognates: Sanskrit dhaman- "law," Greek themis "law," Lithuanian dome "attention"), literally "to set, put" (see factitious). A book of laws in Old English was a dombec. Modern sense of "fate, ruin, destruction" is c.1600, from the finality of the Christian Judgment Day.
doom (v.) Look up doom at Dictionary.com
late 14c., from doom (n.). Related: Doomed; dooming.
Doomsday (n.) Look up Doomsday at Dictionary.com
Old English domes dæg, from domes, genitive of dom (see doom (n.)) + dæg "day" (see day (n.)).

In medieval England it was expected when the world's age reached 6,000 years from creation, which was thought to have been in 5200 B.C. Bede, c.720, complained of being pestered by rustici asking him how many years till the sixth millennium ended. There is no evidence for a general panic in the year 1000 C.E. Doomsday machine "bomb powerful enough to wipe out human life on earth" is from 1960.
door (n.) Look up door at Dictionary.com
Middle English merger of Old English dor (neuter; plural doru) "large door, gate," and Old English duru (fem., plural dura) "door, gate, wicket;" both from Proto-Germanic *dur- (cognates: Old Saxon duru, Old Norse dyrr, Danish dør, Old Frisian dure, Old High German turi, German Tür).

The Germanic words are from PIE *dhwer- "a doorway, a door, a gate" (cognates: Greek thyra, Latin foris, Gaulish doro "mouth," Gothic dauro "gate," Sanskrit dvárah "door, gate," Old Persian duvara- "door," Old Prussian dwaris "gate," Russian dver' "a door").

The base form is frequently in dual or plural, leading to speculation that houses of the original Indo-Europeans had doors with two swinging halves. Middle English had both dure and dor; form dore predominated by 16c., but was supplanted by door.
A door is what a dog is perpetually on the wrong side of. [Ogden Nash]
doorbell (n.) Look up doorbell at Dictionary.com
c.1815, from door + bell (n.).
doorknob (n.) Look up doorknob at Dictionary.com
1847, American English, from door + knob.
doormat (n.) Look up doormat at Dictionary.com
1660s, from door + mat. Figurative use from 1861.
doorstep (n.) Look up doorstep at Dictionary.com
1810, from door + step (n.).
doorway (n.) Look up doorway at Dictionary.com
1799, from door + way (n.).
dooryard (n.) Look up dooryard at Dictionary.com
c.1764, American English, from door + yard (n.1).
doozy Look up doozy at Dictionary.com
also doozie, 1903 (adj.), 1916 (n.), perhaps an alteration of daisy, or from popular Italian actress Eleonora Duse (1859-1924). In either case, reinforced by Duesenberg, the expensive, classy make of automobile from the 1920s-30s.
dopamine Look up dopamine at Dictionary.com
1959, from DOPA, the amino acid (from first letter of elements of dioxyphenylalanine), + -amine.
dope (n.) Look up dope at Dictionary.com
1807, American English, "sauce, gravy, thick liquid," from Dutch doop "thick dipping sauce," from doopen "to dip" (see dip (v.)). Extension to "drug" is 1889, from practice of smoking semi-liquid opium preparation. Meaning "foolish, stupid person" is older (1851) and may have a sense of "thick-headed." Sense of "inside information" (1901) may come from knowing before the race which horse had been drugged to influence performance. Dope-fiend is attested from 1896.
dope (v.) Look up dope at Dictionary.com
1889, from dope (n.). Related: Doped; doping.
dopey (adj.) Look up dopey at Dictionary.com
1896, from dope (n.) + -y (2).
doppelganger (n.) Look up doppelganger at Dictionary.com
1830, from German Doppelgänger, literally "double-goer," originally with a ghostly sense. See double + gang (n.). Sometimes half-anglicized as doubleganger.
Doppler Look up Doppler at Dictionary.com
1871, in reference to Christian Doppler (1803-1853), Austrian scientist, who in 1842 explained the effect of relative motion on waves (originally to explain color changes in binary stars); proved by musicians performing on a moving train. Doppler shift is the change of frequency resulting from the Doppler effect. The surname is literally "Gambler."
Dora Look up Dora at Dictionary.com
fem. proper name, short for Dorothy, Dorothea.
Dorcas Look up Dorcas at Dictionary.com
fem. proper name, from Greek dorkas "gazelle, deer." Dorcas Society "ladies' meeting to make clothes for the poor" (1832) is from Acts ix:36-41.
Dorchester Look up Dorchester at Dictionary.com
Old English Dorcanceaster, earlier Dornwaraceaster, from Latin Durnovaria, from Romano-British *duro- "walled town."
dord (n.) Look up dord at Dictionary.com
1934, a ghost word printed in "Webster's New International Dictionary" and defined as a noun used by physicists and chemists, meaning "density." In sorting out and separating abbreviations from words in preparing the dictionary's second edition, a card marked "D or d" meaning "density" somehow migrated from the "abbreviations" stack to the "words" stack. The "D or d" entry ended up being typeset as a word, dord, and defined as a synonym for density. The mistake was discovered in 1939.
Dorian (adj.) Look up Dorian at Dictionary.com
c.1600, in reference to the mode of ancient Greek music, literally "of Doris," from Greek Doris, district in central Greece, traditionally named for Doros, legendary ancestor of the Dorians, whose name is probably related to doron "gift" (see date (n.1)).
Doric (adj.) Look up Doric at Dictionary.com
1560s, see Dorian; in reference to the architectural order, 1610s. The Doric dialect in ancient Greek theater was broad and rustic, hence it has been applied in English to northern and Scots dialects (1837).
dork (n.) Look up dork at Dictionary.com
"stupid person," 1967, originally U.S. student slang, perhaps from earlier meaning "penis" (1964), itself probably an alteration of dick. Related: Dorky; dorkiness.
dorm (n.) Look up dorm at Dictionary.com
1900, colloquial shortening of dormitory.
dormancy (n.) Look up dormancy at Dictionary.com
1723; see dormant + -cy. Middle English had dormitation "sleep, sleeping" (mid-15c.)
dormant (adj.) Look up dormant at Dictionary.com
late 14c., "fixed in place," from Old French dormant (12c.), present participle of dormir "to sleep," from Latin dormire "to sleep," from PIE root *drem- "to sleep" (cognates: Old Church Slavonic dremati "to sleep, doze," Greek edrathon "I slept," Sanskrit drati "sleeps"). Meaning "in a resting situation" (in heraldry) is from c.1500. Meaning "sleeping' is from 1620s.
dormer (n.) Look up dormer at Dictionary.com
1590s, originally "window of a sleeping room," from Middle French dormeor "sleeping room," from dormir "to sleep" (see dormant).
dormitory (n.) Look up dormitory at Dictionary.com
mid-15c., from Latin dormitorium "sleeping place," from dormire "to sleep" (see dormant). Old English had slæpern "dormitory," with ending as in barn.
dormouse (n.) Look up dormouse at Dictionary.com
early 15c., possibly from Anglo-French *dormouse "tending to be dormant" (from stem of dormir "to sleep," see dormer), with the second element mistaken for mouse; or perhaps it is from a Middle English dialectal compound of mouse and Middle French dormir. The rodent is inactive in winter. French dormeuse, fem. of dormeur "sleeper" is attested only from 17c.
Dorothy Look up Dorothy at Dictionary.com
fem. proper name, from French Dorothée, from Latin Dorothea, from Greek, literally "gift of God," from doron "gift" (see date (n.1)) + fem. of theos "god" (see theo-). With the elements reversed, it becomes Theodora. The accessory called a Dorothy bag is so called from 1907.
dorsal (adj.) Look up dorsal at Dictionary.com
early 15c., from Old French dorsal (14c.) or directly from Medieval Latin dorsalis, corresponding to Latin dorsualis "of the back," from dorsum "back," of uncertain origin.
dory (n.1) Look up dory at Dictionary.com
"small, flat-bottomed boat," 1709, American English, perhaps from a West Indian or Central American Indian language.
dory (n.2) Look up dory at Dictionary.com
type of edible fish, mid-15c., from Old French doree, originally the fem. past participle of dorer "to gild," from Latin deauratus, past participle of deaurare, from de-, here probably intensive, + aurare "to gild," from aurum (see aureate). So called in reference to its colorings.
dosage (n.) Look up dosage at Dictionary.com
1867; see dose + -age, perhaps on model of French dosage (1812).
dose (n.) Look up dose at Dictionary.com
early 15c., "the giving of medicine (in a specified amount or at a stated time)," from Middle French dose (15c.) or directly from Late Latin dosis, from Greek dosis "a portion prescribed," literally "a giving," used by Galen and other Greek physicians to mean an amount of medicine, from stem of didonai "to give" (see date (n.1)). Slang meaning "venereal disease" is from 1914.
dose (v.) Look up dose at Dictionary.com
1650s, from dose (n.). Related: Dosed; dosing.
dossier (n.) Look up dossier at Dictionary.com
1880, from French dossier "bundle of papers," from dos "back" (12c.), from Vulgar Latin dossum, variant of Latin dorsum "back" (see dorsal). Supposedly so called because the bundle bore a label on the back, or possibly from resemblance of the bulge in a mass of bundled papers to the curve of a back. Old French dossiere meant "back-strap, ridge strap (of a horse's harness)."
dot (n.) Look up dot at Dictionary.com
Old English dott "speck, head of a boil," perhaps related to Norwegian dot "lump, small knot," Dutch dot "knot, small bunch, wisp," Old High German tutta "nipple;" ultimate origin unclear.

Known from a single source c.1000; the word reappeared with modern meaning "mark" c.1530; not common until 18c. Morse telegraph sense is from 1838. On the dot "punctual" is 1909, in reference to a clock dial face. Dot-matrix first attested 1975.