'Twelvemonth' definitions:

Definition of 'twelvemonth'

From: WordNet
noun
A period of time containing 365 (or 366) days; "she is 4 years old"; "in the year 1920" [syn: year, twelvemonth, yr]

Definition of 'Twelvemonth'

From: GCIDE
  • Twelvemonth \Twelve"month\, n. A year which consists of twelve calendar months. [1913 Webster]
  • I shall laugh at this a twelvemonth hence. --Shak. [1913 Webster]