[ trahy-an-yoo-uh l ]
/ traɪˈæn yu əl /
done, occurring, issued, etc., three times a year.
a triannual publication, contest, etc.
Related formstri·an·nu·al·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Word Origin and History for triannual
Online Etymology Dictionary, © 2010 Douglas Harper