From Longman Dictionary of Contemporary Englishtwelvetwelve /twelv/ ●●● S3 W2 number HMNthe number 12 → dozen He received a twelve-month jail sentence. Come at twelve (=12 o'clock). Their son Dylan is twelve (=12 years old). —twelfth adjective, pronoun her twelfth birthday in the twelfth century I’m planning to leave on the twelfth (=the 12th day of the month).Origin twelve Old English twelf