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English Words Starting With B

10,030 entries — pick a word to see its definition, pronunciation, and usage.

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Noun Verb Adjective Adverb Plural noun Combining form Verb (transitive)Verb (intransitive)Verb (ambitransitive)

bioweapon
nounC2
/ˈbaɪəʊˌwepən/A biological weapon; a harmful biological agent, such as a pathogen or toxin, deliberately used in warfare or terrorism to cause illness or death.
bipack
nounVery Rare / Technical
/ˈbaɪpæk/A pair of films (or their corresponding images) exposed and processed together, specifically two colour-sensitive emulsion layers on separate film strips in a single film unit, used historically in colour cinematography and photography.
biped
adjectivenounC1
/ˈbaɪ.ped/An animal that uses only two legs for walking.
bipedalism
nounC2
/ˌbaɪˈpiːd(ə)lɪz(ə)m/The condition of using two legs for walking.
biphasic pill
nounLow
/ˌbaɪˈfeɪzɪk ˈpɪl/An oral contraceptive containing two distinct doses or types of hormones, taken in two phases across a monthly cycle.
biphenyl
nounC2
/baɪˈfiːn(ə)l/An organic chemical compound consisting of two benzene rings linked by a single bond.
bipinnaria
nounUltra Rare
/ˌbaɪ.pɪˈnɛə.ri.ə/A larval stage of many starfish, characterized by two rows of ciliated projections on each side.
biplane
nounC1
/ˈbaɪ.pleɪn/An early type of fixed-wing aircraft with two sets of wings, one above the other.
bipod
nounC1
/ˈbaɪ.pɒd/A two-legged support stand.
bipolar disorder
nounC1
/ˌbaɪˈpəʊlə dɪsˈɔːdə/A mental health condition characterized by extreme mood swings that include emotional highs (mania or hypomania) and lows (depression).
bippy
nounVery Low
/ˈbɪp.i/A playful or humorous informal term for a person's rear end or posterior.
biprism
nounC2
/ˈbaɪ.prɪz.əm/A prism with a highly obtuse angle, used especially in optics to produce two virtual images of a single source, enabling interference experiments.
bipropellant
nounVery Low (C2/Technical)
/ˌbaɪ.prəʊˈpel.ənt/A rocket propellant consisting of two separate substances (typically a fuel and an oxidizer) that are stored separately and combined in the combustion chamber.
bipyramid
nounLow
/ˌbaɪˈpɪr.ə.mɪd/A geometric solid formed by two pyramids joined base to base.
biquadrate
nounVery rare / Obsolete
/baɪˈkwɒd.rət/(noun) The fourth power of a number; a number raised to the exponent 4.
biquadratic
adjectivenounVery Low
/ˌbaɪkwɒˈdrætɪk/Of or relating to the fourth power of a number or algebraic expression.
biradical
nounRare / Specialized
/ˌbaɪˈræd.ɪ.kəl/In linguistics (especially Semitic studies), a root consisting of two consonants or radicals, as opposed to the more common triliteral (three-consonant) root.
biratnagar
nounVery Low (Proper Noun)
/ˌbɪr.ətˈnɑː.ɡər/A major city and urban centre in southeastern Nepal.
birch
adjectivenounverb+1B2
/bɜːtʃ/A slender, fast-growing deciduous tree with thin, peeling bark, typically having small leaves and producing catkins.
birch beer
nounLow (Regional/Archaic)
/bɜːtʃ bɪə/A carbonated soft drink, often non-alcoholic, historically or traditionally flavored with extracts from the bark, sap, or twigs of birch trees.

Showing 4601–4620 of 10030 words.