fifteenth letter of the alphabet, from a character that in Phoenician was called 'ain (literally "eye") and represented "a very peculiar and to us unpronounceable guttural" [Century Dictionary]. The Greeks also lacked the sound, so when they adopted the Phoenician letters they arbitrarily changed O's value to a vowel. (Thus there is no grounds for the belief that the form of the letter represents the shape of the mouth in pronouncing it.) The Greeks later added a special character for "long" O (omega), and the original became "little o" (omicron).
In Middle English and later colloquial use, o or o' can be an abbreviation of on or of, and is still literary in some words (o'clock, Jack-o'-lantern, tam-o'-shanter, cat-o'-nine-tails, will-o'-the-wisp, etc.).
O' the common prefix in Irish surnames is from Irish ó, ua (Old Irish au, ui) "descendant."
The "connective" -o- is the usual connecting vowel in compounds taken or formed from Greek, where it often is the vowel in the stem. "[I]t is affixed, not only to terms of Greek origin, but also to those derived from Latin (Latin compounds of which would have been formed with the L. connecting or reduced thematic vowel, -i), especially when compounds are wanted with a sense that Latin composition, even if possible, would not warrant, but which would be authorized by the principles of Greek composition." [OED]
As "zero" in Arabic numerals it is attested from c. 1600, from the similarity of shape. Similarly the O blood type (1926) was originally "zero," denoting the absence of A and B agglutinogens.
As a gauge of track in model railroads, by 1905. For o as an interjection of fear, surprise, joy, etc., see oh.
The use of the colloquial or slang -o suffix in wino, ammo, combo, kiddo, the names of the Marx Brothers, etc., "is widespread in English-speaking countries but nowhere more so than in Australia" [OED].
late 14c., "barb of an arrow," from Old French barbe "beard, beard-like appendage" (11c.), from Latin barba "beard," from Proto-Italic *farfa- "beard," which might be from a common PIE root *bhardhā- "beard" (source also of Old Church Slavonic brada, Russia boroda, Lithuanian barzda, Old Prussian bordus), but according to De Vaan the vowel "rather points to a non-IE borrowing into the European languages."
1701, especially with reference to the system of Hebrew vowel points first established by the Masora (also Massorah), "the tradition by which Jewish scholars endeavor to fix the correct text of the Old Testament and preserve it from corruption," also "a book or marginal notes which preserve the results of the effort," from Hebrew, literally "tradition." One who studies Masora is a Masorete (1580s) or Masorite.
1590s, a legal term, "to annul, do away with," from French elider (16c.), from Latin elidere "strike out, force out," in grammar "suppress (a vowel)" from ex "out" (see ex-) + -lidere, combining form of laedere "to strike" (see collide). The Latin word in grammatical use translates Greek ekthlibein. Phonological sense "slurring over a sound or part of a word" in English is first recorded 1796. Related: Elided; eliding.
"to soak stems of fibrous plants (flax, hemp, jute, etc.) to soften them," mid-15c., probably from Middle Dutch roten (or an unrecorded cognate Old Norse word that is related to Norwegian røyta, Swedish röta, Danish røde); the group is considered to be related to Old English rotian "to rot" (see rot (v.)), but the vowel is difficult. The process partially rots the stems so the workers may better get the fibers.
early 14c., "alphabetic element other than a vowel," from Latin consonantem (nominative consonans) "sounding together, agreeing," as a noun, "a consonant" (consonantem littera), present participle of consonare "to sound together, sound aloud," from assimilated form of com "with, together" (see con-) + sonare "to sound, make a noise" (from PIE root *swen- "to sound").
Consonants were thought of as sounds that are produced only together with vowels. Related: Consonantal.
"one of the external openings of the nose, a nasal orifice," late 14c., nostrille, from Old English nosþyrl, nosðirl, literally "the hole of the nose," from nosu "nose" (from PIE root *nas- "nose") + þyrel "hole" (from PIE root *tere- (2) "cross over, pass through, overcome"). For metathesis of -r- and vowel, see wright. After the second element became obsolete as an independent, its form was corrupted in the compound.