Online Etymology Dictionary

-ule: word-forming element meaning "small, little" (capsule, module, etc.), from French -ule, from Latin diminutive suffix -ulus (fem. -ula, neuter -ulum).
-ulent: word-forming element, from Latin adjective suffix -ulentus "full of."
-ure: suffix forming abstract nouns of action, from Old French -ure, from Latin -ura.
u: for historical evolution, see V. Used punningly for you by 1588 ["Love's Labour's Lost," V.i.60], not long after the pronunciation shift that made the vowel a homonym of the pronoun. As a simple shorthand (without intentional word-play), it is recorded from 1862. Common in business abbreviations since 1923 (e.g. U-Haul, attested from 1951).
U-bahn: German or Austrian subway system, 1938 (originally in reference to Berlin), from German U-bahn, short for Untergrund-bahn, literally "underground railway."
U-boat: 1916 (said to have been in use from 1913), partial translation of German U-Boot, short for Unterseeboot, literally "undersea boat."
U-turn (n.): 1934, from u + turn (n.). So called in reference to the shape of the path described.
U.K.: abbreviation for United Kingdom, attested from 1892.
U.N.: abbreviation for United Nations, attested from 1946.
U.S.: abbreviation for United States, attested from 1834.
ubi: "place, location, position," 1610s, common in English c.1640-1740, from Latin ubi "where," ultimately from PIE *kwo-bhi- (cf. Sanskrit kuha, Old Church Slavonic kude "where"), locative case of pronomial base *kwo-. Ubi sunt, literally "where are" (1914), in reference to lamentations for the mutability of things is from a phrase used in certain Medieval Latin Christian works.
ubiquitous (adj.): "turning up everywhere," 1837, from ubiquity + -ous. The earlier word was ubiquitary (1580s), from Modern Latin ubiquitarius, from ubique. Related: Ubiquitously; ubiquitousness.
ubiquity (n.): 1570s, from Middle French ubiquité (17c.), from Latin ubique "everywhere," from ubi "where" (see ubi) + que "any, also, ever," a suffix that can give universal meaning to the word it is attached to. Originally a Lutheran theological position maintaining the omnipresence of Christ.
udder (n.): Old English udder "milk gland of a cow, goat, etc.," from Proto-Germanic *udr- (cf. Old Frisian and Middle Dutch uder, Old High German utar, German Euter, and, with unexplained change of consonant, Old Norse jugr), from PIE *udhr- (cf. Sanskrit udhar, Greek outhar, Latin uber "udder").
UFO (n.): 1953, abbreviation of Unidentified Flying Object, which is attested from 1950.
ufology (n.): 1959, from UFO + -logy.
ug (v.): early 13c., "to inspire fear or loathing;" mid-14c. "to feel fear or loathing," from Old Norse ugga "to fear, dread" (see ugly).
Uganda: from Swahili u "land, country" + Ganda, indigenous people name, of unknown origin.
Ugaritic: 1936, "pertaining to Ugarit," ancient city of northern Syria, and especially to the language first discovered there 1929 by Claude Schaeffer, from Ugarit, which probably is ultimately from Sumerian ugaru "field."
ugh: 1765, imitative of the sound of a cough; as an interjection of disgust, recorded from 1837.
uglify (v.): 1570s; see ugly + -fy. Related: uglified; uglifying.
ugly (adj.): mid-13c., uglike "frightful or horrible in appearance," from Old Norse uggligr "dreadful, fearful," from uggr "fear, apprehension, dread" (perhaps related to agg "strife, hate") + -ligr "-like." Meaning softened to "very unpleasant to look at" late 14c. Extended sense of "morally offensive" is attested from c.1300; that of "ill-tempered" is from 1680s.

Among words for this concept, ugly is unusual in being formed from a root for "fear, dread." More common is a compound meaning "ill-shaped" (e.g. Greek dyseides, Latin deformis, Irish dochrud, Sanskrit ku-rupa). Another Germanic group has a root sense of "hate, sorrow" (see loath). Ugly duckling (1877) is from the story by Hans Christian Andersen, first translated from Danish to English 1846. Ugly American "U.S. citizen who behaves offensively abroad" is first recorded 1958 as a book title.
uh: inarticulate sound, attested from c.1600; uh-huh, spoken affirmative (often ironic or non-committal) is recorded from 1904; negative uh-uh is attested from 1924.
UHF: 1937, abbreviation of ultra-high frequency (1932) in reference to radio frequencies in the range of 300 to 3,000 megahertz.
uhlan (n.): "cavalryman," 1753, from German Uhlan, from Polish ułan "a lancer," from Turkish oghlan "a youth." For sense evolution, cf. infantry.
ukase (n.): 1729, "decree issued by a Russian emperor," from Russian ukaz "edict," from ukazat' "to show, decree," from Old Church Slavonic ukazati, from u-, intensive prefix, + kazati "to show, order," which is related to the first element of Casimir.
uke: short for ukulele, by 1915.
Ukraine: from Russian Ukraina, literally "border, frontier," from u- "at" + krai "edge."
ukulele (n.): 1896, from Hawaiian 'ukulele, literally "leaping flea," from 'uku "louse, flea" + lele "to fly, jump, leap." So called from the rapid motion of the fingers in playing it. It developed from a Portuguese instrument introduced to the islands c.1879.
ulcer (n.): c.1400, from Old French ulcere, from Vulgar Latin ulcerem, from Latin ulcus (genitive ulceris) "ulcer," from PIE *elk-es- "wound" (cf. Greek elkos).
ulceration (n.): c.1400, from Latin ulcerationem (nominative ulceratio), noun of action from ulcerare, from ulcer (see ulcer).
ulcerous (adj.): 1570s, from Latin ulcerosus, from ulcer (see ulcer).
ulema (n.): "scholars of Muslim religious law," 1680s, from Arabic 'ulema "learned men, scholars," plural of 'alim "learned," from 'alama "to know."
ullage (n.): "amount by which a cask or bottle falls short of being full," late 15c., from Anglo-French ulliage (early 14c.), Anglo-Latin oliagium (late 13c.), Old French ouillage, from ouiller "to fill up (a barrel) to the bung," literally "to fill to the eye," from ueil "eye," from Latin oculus (see eye (n.)).
ulna (n.): inner bone of the forearm, 1540s, Latin, literally "elbow;" related to Old English eln (see elbow (n.)).
Ulrich: masc. proper name, German, from Old High German Uodalrich, literally "of a rich home," from uodal "home, nobility" (related to Old English æðele "noble," Old Norse oðal "home").
Ulster: northernmost of the four provinces of Ireland, 14c., from Anglo-French Ulvestre (early 13c.), Anglo-Latin Ulvestera (c.1200), corresponding to Old Norse Ulfastir, probably from Irish Ulaidh "men of Ulster" + suffix also found in Leinster, Munster, and perhaps representing Irish tir "land."
ult.: see ultimo.
ulterior (adj.): 1640s, from Latin ulterior "more distant, further," comparative of *ulter "beyond" (see ultra-). The sense in ulterior motives is first attested 1735.
ultimate (adj.): 1650s, from Late Latin ultimatus, past participle of ultimare "to be final, come to an end," from ultimus "last, final," superlative of *ulter "beyond" (see ultra-). Ultimate Frisbee is attested from 1972.
ultimatum (n.): 1731, from Modern Latin, from Medieval Latin adjective ultimatum "last possible, final," from Latin ultimatum, neuter of ultimatus (see ultimate). Hamilton and others use the Latin plural ultimata. In slang c.1820s, ultimatum was used for "the buttocks."
ultimo: "in the month preceding the present," 1610s, common in abbreviated form ult. in 18c.-19c. correspondence and newspapers, from Latin ultimo (mense) "of last (month)," ablative singular masc. of ultimus "last" (see ultimate). Earlier it was used in the sense of "on the last day of the month specified" (1580s). Contrasted with proximo "in the next (month)," from Latin proximo (mense).
ultra vires: Latin, literally "beyond powers," from vires "strength, force, vigor, power," plural of vis.
ultra-: prefix meaning "beyond" (ultraviolet) or "extremely" (ultramodern), from Latin ultra- from ultra (adv. and prep.) "beyond, on the further side," from PIE *al- "beyond." In common use from early 19c., it appears to have arisen from French political designations. As its own word, a noun meaning "extremist" of various stripes, it is first recorded 1817, from French ultra, shortening of ultra-royaliste "extreme royalist."
ultralight (adj.): 1974, from ultra- + light (adj.). As a noun meaning "ultralight aircraft" it is recorded from 1982.
ultramarine (n.): 1590s, "blue pigment made from lapis lazuli," from Medieval Latin ultramarinus, literally "beyond the sea," from ultra- "beyond" + marinus "of the sea" (see marine). So called because the mineral was imported from Asia by sea.
ultramontane (adj.): 1590s, from Middle French ultramontain "beyond the mountains" (especially the Alps), from Old French (early 14c.), from Latin ultra "beyond" (see ultra-) + stem of mons (see mount (n.)). Used especially of papal authority, though "connotation varies according to the position of the speaker or writer." [Weekley]
ultranationalism (n.): also ultra-nationalism, by 1853, from ultra- + nationalism.
ultrasonic (adj.): 1923, "having frequency beyond the audible range," from ultra- + sonic. For sense, see supersonic.
ultrasonography (n.): 1960, from ultra- + sonography (see sonogram).