y

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The 25th letter of the modern English alphabet.
• noun Any of the speech sounds represented by the letter y.
• noun The 25th in a series.
• noun Something shaped like the letter Y.

from The Century Dictionary.

• noun A diminutive suffix, appearing chiefly in childish names of animals, etc., as kitty, doggy, piggy, birdy, froggy, mousy, and similar names, or familiar forms of personal names, as Katy or Kitty (diminutive of Kate), Jenny, Hetty, Fanny, Willy, Johnny, Tommy, etc., such names being often spelled with -ie, as Willie, Davie, etc., a spelling common in Scotch use, and also in general use in names of girls, as Katie, Jennie, Hettie, Carrie, Lizzie, Nellie, Annie, etc.
• noun An old mode of writing the pronoun I.
• The twenty-fifth letter in the English alphabet.
• As a symbol:
• In chem., the symbol of yttrium.
• In ornithology, in myological formulas, the symbol of the accessory semitendinosus.
• In mathematics:
• [lowercase] In algebra, the second of the variables or unknown quantities.
• [lowercase] In analytical geometry, the symbol of the ordinate or other rectilinear point-coördinate.
• In mechanics, the component of a force in the direction of the axis of y.
• As a medieval Roman numeral, the symbol for 150, and with a line drawn above it (Y), 150,000.
• [lowercase] An abbreviation of year.
• In electricity, the symbol for admittance, in alternating-current circuits. See admittance, 6.
• [lowercase] An abbreviation of yard.
• [lowercase or cap.] A corruption of the Anglo-Saxon character , equivalent to th, giving ye for the or thee; and, by contraction, ym for them; yn for then; yr for their; ys for this; yt for that. See def. 1.
• noun See i-. For Middle English words with this prefix, see i-, or the form without the prefix.
• noun A very common suffix used to form adjectives from nouns, and sometimes from verbs, such adjectives denoting ‘having,’ ‘covered with,’ ‘full of,’ etc., the thing expressed by the noun, as in stony, rocky, icy, watery, rainy, dewy, meaty, juicy, mealy, salty, peppery, powdery, flowery, spotty, speckly, etc.
• noun A termination of nouns from the Latin or Greek, or of modern formation on the Latin or Greek model.
• noun Something resembling the letter Y in shape.

from the GNU version of the Collaborative International Dictionary of English.

• noun One of the forked holders for supporting the telescope of a leveling instrument, or the axis of a theodolite; a wye.
• noun A forked or bifurcated pipe fitting.
• noun (Railroads) A portion of track consisting of two diverging tracks connected by a cross track.
• noun (Surv.) an instrument for measuring differences of level by means of a telescope resting in Y's.
• noun (Zoöl.) a handsome European noctuid moth Plusia gamma) which has a bright, silvery mark, shaped like the letter Y, on each of the fore wings. Its larva, which is green with five dorsal white species, feeds on the cabbage, turnip, bean, etc. Called also gamma moth, and silver Y.
• pronoun obsolete I.
• Y, the twenty-fifth letter of the English alphabet, at the beginning of a word or syllable, except when a prefix (see Y-), is usually a fricative vocal consonant; as a prefix, and usually in the middle or at the end of a syllable, it is a vowel. See Guide to Pronunciation, §§ 145, 178-9, 272.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The twenty-fifth letter of the basic modern Latin alphabet.
• noun metrology Symbol for the prefix yocto-.
• noun close front rounded vowel
• noun Denoting an item that is twenty-fifth in a list.
• noun The twenty-fifth letter of the English alphabet, called wye and written in the Latin script.
• abbreviation Abbreviation of year.
• abbreviation UK, television Abbreviation of youth., usually followed by an age appropriate for the content so marked.
• abbreviation computing Abbreviation of yes.
• abbreviation slang, text messaging, Internet Abbreviation of why.?

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the 25th letter of the Roman alphabet
• noun a silvery metallic element that is common in rare-earth minerals; used in magnesium and aluminum alloys