- bismuth
WordReference Random House Learner's Dictionary of American English © 2026
bi /baɪ/USA pronunciation
adj., n. [countable], pl.
bi-,1 prefix.
bi-2,
WordReference Random House Unabridged Dictionary of American English © 2026- Slang Termsbis, bi's. Slang. bisexual.
bi-,1 prefix.
- bi- comes from Latin, where it has the meaning "twice, two.'' This meaning is found in such words as: bicentennial, biennial, bigamy, bilateral, binoculars, bipartisan, biped, bisect, biweekly.
- In some words, esp. words referring to time periods, the prefix bi- has two meanings: "twice a + ~'' and "every two + ~-s''. Thus, biannual means both "twice a year'' and "every two years.'' Be careful; check many of these words.
bi-2,
bi
(bī),USA pronunciation adj., n., pl. bis, bi's.
BI ,pl. BI's.
Bi ,[Symbol, Chem.]
bi-1 ,
bi-2 ,
WordReference Random House Learner's Dictionary of American English © 2026- Slang Termsbisexual.
- by shortening
BI ,pl. BI's.
- built-in.
Bi ,[Symbol, Chem.]
- Chemistrybismuth.
bi-1 ,
- a combining form meaning "twice,'' "two,'' used in the formation of compound words:bifacial; bifarious.Cf. bin-.
- 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).
bi-2 ,
- var. of bio-, esp. before a vowel:biopsy.
bi•o /ˈbaɪoʊ/USA pronunciation
n., pl. bi•os.
bio-, prefix.
WordReference Random House Unabridged Dictionary of American English © 2026- Informal Terms biography:[countable][a bio on the first president of the countablery.]
- Informal Terms biology:[uncountable][I had a rough course in bio last term.]
bio-, prefix.
- bio- comes from Greek, where it has the meaning "life.'' This meaning is found in such words as: biodegradable, biology, biosphere.
bi•o
(bī′ō),USA pronunciation n., pl. bi•os, adj. [Informal.]
n.
adj.
bio-,
n.
- Informal Termsbiography.
- Informal Termsbiology.
adj.
- Informal Termsbiographical.
- Informal Termsbiological:a bio control service using praying mantises to reduce the population of garden pests.
- 1945–50; by shortening; as adjective, adjectival, independent use of bio-, taken as a free form
bio-,
- a combining form meaning "life'' occurring in loanwords from Greek (biography);
on this model, used in the formation of compound words (bioluminescence).
- akin to Latin vīvus living, Sanskrit jīvas. See quick combining form of Greek bíos life
Collins Concise English Dictionary © HarperCollins Publishers::
Bi the chemical symbol for
Collins Concise English Dictionary © HarperCollins Publishers::
bi-, (sometimes before a vowel) bin- combining form
- two; having two: bifocal
- occurring every two; lasting for two: biennial
- on both sides, surfaces, directions, etc: bilateral
- occurring twice during: biweekly
- denoting an organic compound containing two identical cyclic hydrocarbon systems: biphenyl
- (rare in technical usage) indicating an acid salt of a dibasic acid: sodium bicarbonate
(not in technical usage) equivalent of di-1
bi- combining form
a variant of bio-
'bi' also found in these entries (note: many are not synonyms or translations):
alibi
- balance
- barouche
- be-
- because
- bee
- below
- bi-
- bicameral
- biceps
- bicycle
- bifid
- bifurcate
- bigamy
- billion
- bimanous
- bimonthly
- bin-
- binocular
- binomial
- binomial distribution
- bio-
- bireme
- bisect
- bismuth
- biweekly
- biyearly
- bohrium
- by
- cumulonimbus
- di-
- exbi-
- gamut
- incubus
- kibi-
- mebi-
- nimbus
- oribi
- pebi-
- Poisson distribution
- rhombus
- succubus
- syllabus
- tebi-
- thrombus
- American Bible Society
- American bison
- amputate
- anti-Bible
- astrometric binary
