[ bahy-muhnth-lee ]
/ baɪˈmʌnθ li /


occurring every two months.
occurring twice a month; semimonthly.

noun, plural bi·month·lies.

a bimonthly publication.


every two months: Next year we plan six field trips to take place bimonthly.
twice a month; semimonthly.

Origin of bimonthly

First recorded in 1840–50; bi-1 + monthly
Can be confusedbimonthly biweekly semimonthly (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 bi-monthly

British Dictionary definitions for bi-monthly


/ (baɪˈmʌnθlɪ) /

adjective, adverb

every two months
(often avoided because of confusion with sense 1) twice a month; semimonthlySee bi- 1

noun plural -lies

a periodical published every two months
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

Word Origin and History for bi-monthly



also bi-monthly, 1846, "happening once in two months, every two months," also "occurring twice a month," a hybrid from bi- + monthly.

Online Etymology Dictionary, © 2010 Douglas Harper