[ sem-ee-an-yoo-uh l, sem-ahy- ]
/ ˌsɛm iˈæn yu əl, ˌsɛm aɪ- /


occurring, done, or published every half year or twice a year; semiyearly.
lasting for half a year: a semiannual plant.

Origin of semiannual

First recorded in 1785–95; semi- + annual

Related forms

sem·i·an·nu·al·ly, adverb

Can be confused

biannual biennial semiannual (see usage note at bi-1)

Usage note

See bi-1. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for semiannual

British Dictionary definitions for semiannual


/ (ˌsɛmɪˈænjʊəl) /


occurring every half-year
lasting for half a year

Derived Forms

semiannually, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012