a combining form meaning “twice,” “two,” used in the formation of compound words: bifacial; bifarious.
bi erasureRead more in this article about some frequently asked questions and fun facts related to our definitions.
Origin of bi-1
< Latin, combining form of bis; see twice
All words except biennial referring to periods of time and prefixed by bi-1 are potentially ambiguous. Since bi- can be taken to mean either “twice each” or “every two,” a word like biweekly can be understood as “twice each week” or “every two weeks.” To avoid confusion, it is better to use the prefix semi- to mean “twice each” ( semiannual; semimonthly; semiweekly ) or the phrase twice a or twice each ( twice a month; twice a week; twice each year ), and for the other sense to use the phrase every two ( every two months; every two weeks; every two years ).
Definition for bi- (2 of 2)
variant of bio-, especially before a vowel: biopsy.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for bi- (1 of 2)
sometimes before a vowel bin-
two; having twobifocal
occurring every two; lasting for twobiennial
on both sides, surfaces, directions, etcbilateral
occurring twice duringbiweekly
- denoting an organic compound containing two identical cyclic hydrocarbon systemsbiphenyl
- (rare in technical usage) indicating an acid salt of a dibasic acidsodium bicarbonate
- (not in technical usage) equivalent of di- 1 (def. 2a)
Word Origin for bi-
from Latin, from bis twice
British Dictionary definitions for bi- (2 of 2)
a variant of bio-
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