u Meaning, Definition & Usage

  1. noun a base containing nitrogen that is found in RNA (but not in DNA) and derived from pyrimidine; pairs with adenine
    uracil.
  2. noun a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons
    uranium; atomic number 92.
  3. noun the 21st letter of the Roman alphabet
  4. adjective satellite (chiefly British) of or appropriate to the upper classes especially in language use

WordNet

U
Definitions
  1. , the twenty-first letter of the English alphabet, is a cursive form of the letter V, with which it was formerly used interchangeably, both letters being then used both as vowels and consonants. U and V are now, however, differentiated, U being used only as a vowel or semivowel, and V only as a consonant. The true primary vowel sound of U, in Anglo-Saxon, was the sound which it still retains in most of the languages of Europe, that of long oo, as in tool, and short oo, as in wood, answering to the French ou in tour. Etymologically U is most closely related to o, y (vowel), w, and v; as in two, duet, dyad, twice; top, tuft; sop, sup; auspice, aviary. See V, also O and Y. See Guide to Pronunciation, §§ 130-144.

Webster 1913