Online Etymology Dictionary

ultrasound: 1923, from ultra- + sound. Cf. ultrasonic. In reference to ultrasonic techniques of detection or diagnosis it is recorded from 1958.
ultraviolet: "beyond the violet end of the visible spectrum," 1840, from ultra- + violet. Ultra-red (1870) was a former name for what now is called infra-red.
ululate (v.): 1620s, from Latin ululatus, past participle of ululare (see ululation). Related: Ululated; ululating.
ululation (n.): 1590s, from Latin ululationem (nominative ululatio) "a howling or wailing," noun of action from past participle stem of ululare "ululate," a reduplicated imitative root (cf. Greek ololyzein "to cry aloud," Sanskrit ululih "a howling," Lithuanian uluti "howl," Gaelic uileliugh "wail of lamentation," Old English ule "owl").
Ulysses: Latin name for Odysseus, from Latin Ulysses, Ulixes. Famous for wandering as well as craftiness and ability at deceit. For -d- to -l- alteration, see lachrymose.
um: a sound denoting hesitation, 1670s.
Umayyad: "member of a Muslim dynasty which ruled the Caliphate 661-750 C.E. and in 756 C.E. founded an emirate in Spain," 1758, from Arabic, from Umayya, proper name of an ancestor of Muhammad from whom the dynasty claimed descent.
umbel: 1590s, from Latin umbella "parasol," diminutive of umbra (see umbrage).
umber (n.): brown earthy pigment, 1560s, from Middle French ombre (in terre d'ombre), or Italian ombra (in terra di ombra), both from either Latin umbra "shade, shadow" (see umbrage) or from Umbra, fem. of Umber "belonging to Umbria," region in central Italy from which the coloring matter first came. Burnt umber, specially prepared and redder in color, is attested from c.1650.
umbilical (adj.): "pertaining to the navel," 1540s, from Medieval Latin umbilicalis "of the navel," from Latin umbilicus "navel" (see umbilicus). Umbilical cord attested by 1753 (the native term is navel string).
umbilicus (n.): "navel," 1610s, from Latin umbilicus "navel," from PIE root *(o)nobh- "navel" (see navel). In English, mostly confined to medical writing. Latin umbilicus is source of Spanish ombligo as well as Old French lombril, literally "the navel," from l'ombril, which by dissimilation became modern Fr. nombril (12c.).
umbles (n.): "edible inner parts of a deer or other animal," c.1400, see humble.
umbo: 1921, from Latin umbo "shield-boss, knob, projection."
umbra (n.): 1590s, "phantom, ghost," a figurative use from Latin umbra "shade, shadow" (see umbrage). Astronomical sense of "shadow cast by the earth or moon during an eclipse" is first recorded 1670s. Meaning "an uninvited guest accompanying an invited one" is from 1690s.
umbrage (n.): early 15c., "shadow, shade," from Middle French ombrage "shade, shadow," from Latin umbraticum, neuter of umbraticus "of or pertaining to shade," from umbra "shade, shadow," from PIE root *andho- "blind, dark" (cf. Sanskrit andha-, Avestan anda- "blind, dark"). Many figurative uses in 17c.; main remaining one is the meaning "suspicion that one has been slighted," first recorded 1610s; hence phrase to take umbrage at, attested from 1670s.
umbrageous (adj.): "shady," 1580s, from French ombrageux, from Old French umbrageus, from umbre "shade," from Latin umbra (see umbrage).
umbrella (n.): c.1600, first attested in Donne's letters, from Italian ombrello, from Late Latin umbrella, altered (by influence of umbra) from Latin umbella "sunshade, parasol," diminutive of umbra "shade, shadow" (see umbrage).

A sunshade in the Mediterranean, a shelter from the rain in England; in late 17c. usage, usually as an Oriental or African symbol of dignity. Said to have been used by women in England from c.1700; the first rain-umbrella carried by a man there was traditionally c.1760, by Jonas Hathaway, noted traveler and philanthropist. Figurative sense of "authority, unifying quality" (usually in a phrase such as under the umbrella of) is recorded from 1948.
umiak (n.): "large Eskimo boat," c.1743, from Eskimo umiaq "an open skin boat." Said by 18c.-19c. sources to be a "woman's boat," as opposed to the kayak, which was worked exclusively by men.
umlaut (n.): 1852, from German umlaut "change of sound," from um "about" (see ambi-) + laut "sound," from Old High German hlut (see listen). Coined 1774 by poet Friedrich Gottlieb Klopstock (1724-1803) but first used in its current sense 1819 by linguist Jakob Grimm (1785-1863).
umma (n.): "the Islamic community," founded by Muhammad and bound to one another by religious ties and obligations, 1855, from Arabic 'umma "people, community, nation."
ump (n.): short for umpire (n.), by 1915, American English.
umpire (n.): c.1400, noumper, from Old French nonper "odd number, not even," in reference to a third person to arbitrate between two, from non "not" + per "equal," from Latin par. Initial -n- lost by mid-15c. due to faulty separation of a noumpere, heard as an oumpere. Originally legal, the gaming sense first recorded 1714 (in wrestling).
umpire (v.): c.1600, from umpire (n.). Related: Umpired; umpiring.
umpteen: 1917, World War I army slang, from umpty + teen. Related: Umpteenth.
umpty: 1905, "of an indefinite number," originally Morse code slang for "dash," influenced by association with numerals such as twenty, thirty, etc.
un- (1): prefix of negation, Old English un-, from Proto-Germanic *un- (cf. Old Frisian, Old High German, German un-, Gothic un-, Dutch on-), from PIE *n- (cf. Sanskrit a-, an- "not," Greek a-, an-, Old Irish an-, Latin in-), a variant of PIE root *ne- "not" (cf. Avestan na, Old Church Slavonic and Lithuanian ne "not," Latin ne "that not," Greek ne- "not," Old Irish ni, Cornish ny "not").

Freely and widely used since Old English in compounds with native and imported words, it disputes with Latin-derived cognate in- the right to form the negation of certain words (indigestable/undigestable, etc.). Often euphemistic (e.g. untruth for "lie"). The most prolific of English prefixes, it even is used to make words from phrases (e.g. uncalled-for, c.1600; undreamed-of, 1630s; uncome-at-able, 1690s; unputdownable, 1947, of a book; un-in-one-breath-utterable, Ben Jonson; etc., but not restricted to un-; cf. put-up-able-with, 1812). As a prefix in telegram-ese to replace not and save the cost of a word, it is first attested 1936.
un- (2): prefix of reversal (e.g. unhand, undo, unbutton), Old English on-, un-, from Proto-Germanic *andi- (cf. Old Saxon ant-, Old Norse and-, Dutch ont-, Old High German ant-, German ant-, Gothic and- "against"), from PIE *anti "facing opposite, near, in front of, before" (see ante).
un-American (adj.): 1818, from un- (1) "not" + American.
Everything is un-American that tends either to government by a plutocracy or government by a mob. [Theodore Roosevelt, 1917]
un-British (adj.): 1746, from un- (1) "not" + British.
un-English (adj.): "lacking in qualities regarded as typically English," 1630s, from un- (1) "not" + English (1).
unabashed (adj.): 1570s, from un- (1) "not" + past participle of abash. Related: Unabashedly.
unabated (adj.): 1610s, from un- (1) "not" + past participle of abate.
unable (adj.): late 14c., "lacking in ability, incapable," from un- (1) "not" + able. Modeled on Old French inhabile or Latin inhabilis.
unabridged (adj.): 1590s, from un- (1) "not" + past participle of abridge. Since 19c. chiefly in reference to literary works.
unacceptable (adj.): late 15c., from un- (1) "not" + acceptable. Related: Unacceptably.
unaccompanied (adj.): 1540s, "not in the company of others," from un- (1) "not" + past participle of accompany. Musical sense is first recorded 1818.
unaccountable (adj.): 1640s, "inexplicable," from un- (1) "not" + accountable. Meaning "not liable to be called to account" is recorded from 1640s. Related: Unaccountably.
unaccustomed (adj.): 1520s, "not customary, unfamiliar," from un- (1) "not" + past participle of accustom. Meaning "not accustomed or habituated" (to) is first attested 1610s.
unacquainted (adj.): 1520s, from un- (1) "not" + acquainted.
unadorned (adj.): 1630s, from un- (1) "not" + past participle of adorn.
unadulterated (adj.): 1719, from un- (1) "not" + past participle of adulterate.
unadvertised (adj.): mid-15c., "uninformed, unadvised," from un- (1) + advertised.
unaffected (adj.): 1580s, "not influenced, untouched in mind or feeling," from un- (1) "not" + past participle of affect. Meaning "not adopted or assumed, genuine" is recorded from 1590s; that of "not acted upon or altered (by something)" is first attested 1830.
unafraid (adj.): early 15c., from un- (1) "not" + afraid.
unaided (adj.): 1660s, from un- (1) "not" + past participle of aid.
unalienable (adj.): 1610s, from un- (1) "not" + alienable. Related: Unalienably.
unalloyed (adj.): 1670s (figurative); 1760s (literal), from un- (1) "not" + past participle of alloy (v.).
unalterable (adj.): 1610s, from un- (1) + alterable. Related: Unalterably.
unaltered (adj.): 1550s, from un- (1) "not" + past participle of alter.
unambiguous (adj.): 1630s, from un- (1) "not" + ambiguous. Related: Unambiguously.