alphabetic character, in early writing not always distinguished from V and W; for historical evolution, see V. U-turn is attested by 1921, for the shape of the course described by the vehicle.

Attested 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 for you (without intentional word-play), it is recorded by 1862. In the old British movie classification code (1922) it stood for universal, as "suitable for all ages" (equivalent of American G).

Common in business names since 1923 (U-Haul is attested by 1950), earlier in newspaper advertisements (u haul is attested by 1937 in classified ads for large items or lots that must be picked up by the purchaser; while-u-wait for suit cleaning, etc., is by 1911.

The substitution of Middle English -o- for Old English -u- before -m-, -n-, or -r- was a French scribal habit before minims to avoid misreading the letters in the old style handwriting, which jammed them together. The practice transformed some, come, monk, tongue, and worm.

German or Austrian subway system, 1938 (originally in reference to Berlin), from German U-bahn, short for Untergrund-bahn, literally "underground railway." Bahn "path, road" is from Middle High German ban, bane "way, road," literally "strike" (as a swath cut through), according to Watkins from PIE *gwhen- "to strike, kill" (see bane).

"whereness, state of being in a definite place," 1670s, from Modern Latin ubietas, from Latin ubi "where" (see ubi). Related: Ubication "condition or fact of being everywhere" (1640s).

"place, location, position," 1610s, from Latin ubi "where?, in which place, in what place," relative pronominal adverb of place, ultimately from PIE *kwo-bhi- (source also of Sanskrit kuha, Old Church Slavonic kude "where"), locative case of pronominal root *kwo-.

According to OED (1989) common in English c. 1640-1740. Also in classical phrases used in English, such as 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.

Mais où sont les neiges d'antan? [Villon]

"omnipresence, capacity of being in an indefinite number of places at the same time," 1570s, originally theological (of God, Christ), from Modern Latin ubiquitas, from Latin ubique "everywhere," from ubi "where" (see ubi). Second element is -que "and," also "any, also, ever," as a suffix giving universal meaning to the word it is attached to, from PIE root *kwe "and, -ever" (source also of Hittite -kku "now, even, and;" Sanskrit -ca, Avestan -ca "and, also, if;" Greek -te "and;" Gothic -uh "and, also," nih "if not").

Related: Ubiquitary "being everywhere or in all places" (1590s); ubiquitarian "one who exists everywhere" (1727).

"being, existing, or turning up everywhere," 1800, from ubiquity + -ous. The earlier word was ubiquitary (c. 1600), from Modern Latin ubiquitarius, from ubique (see ubiquity). Related: Ubiquitously; ubiquitousness.

"German submarine," 1914, partial translation of German U-Boot, short for Unterseeboot, literally "undersea boat."

Old English udder "milk glands of a cow, goat, etc., when large and baggy and having more than one teat," from Proto-Germanic *udr- (source also of Old Frisian uder, Middle Dutch uyder, Dutch uijer, Old High German utar, German Euter, and, with unexplained change of consonant, Old Norse jugr), from PIE *eue-dh-r "udder" (source also of Sanskrit udhar, Greek outhar, Latin uber "udder, breast," also "fruitful").

1953 as an abbreviation of Unidentified Flying Object, which is attested from 1950 in the popular "flying saucer" sense.

"study of UFOs," 1956, from UFO + -logy.