from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The cardinal number equal to 17 + 1.
  • n. The 18th in a set or sequence.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The cardinal number occurring after seventeen and before nineteen, represented in Roman numerals as XVIII and in Arabic numerals as 18.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Eight and ten.
  • n. The number greater by a unit than seventeen; eighteen units or objects.
  • n. A symbol denoting eighteen units, as 18 or xviii.

from The Century Dictionary and Cyclopedia

  • Eight more than ten, or one more than seventeen: a cardinal numeral.
  • n. The sum of ten and eight, or seventeen and one.
  • n. A symbol representing eighteen units, as 18, or XVIII, or xviii.

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

  • n. the cardinal number that is the sum of seventeen and one
  • adj. being one more than seventeen


Middle English eightetene, from Old English eahtatēne; see oktō(u) in Indo-European roots.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Middle English ehtetene, from Old English eahtatīene, eahtatēne, from Proto-Germanic *ahtōutehun. Compare West Frisian achttjin, Dutch achttien, German achtzehn, Danish atten. (Wiktionary)



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