Grammar and word types

Words with the prefix bi and what it means

The prefix bi- comes from Latin and means two or twice. This list gathers common words built with bi-, from everyday terms like bicycle to more specialized words like bipartisan, to help learners recognize the pattern.

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Words with the prefix bi and what it means

Word	Meaning	In a sentence
bicyclenoun	A two-wheeled vehicle propelled by pedaling and steered with handlebars.	She rode her bicycle to work every morning to avoid traffic.
bicepsnoun	The large muscle at the front of the upper arm that bends the elbow.	He flexed his biceps to show off the results of months of training.
bilingualadjective	Able to speak two languages fluently, or involving the use of two languages.	Growing up in Montreal, she became bilingual in English and French.
bimonthlyadjective	Occurring every two months, or sometimes twice a month.	The book club meets on a bimonthly basis, gathering every other month.
binaryadjective	Relating to a system with only two possible values, states, or options.	Computers store all data using a binary system of ones and zeros.
binocularsnoun	An optical device with two tubes and lenses, used for viewing distant objects with both eyes.	She used binoculars to watch the eagle nesting on the cliff.
biplanenoun	An early type of aircraft with two sets of wings stacked one above the other.	The pilot performed daring loops in a restored biplane at the vintage air show.
bipartisanadjective	Supported by or involving members of two opposing political parties, especially in government.	The senators reached a bipartisan agreement on the infrastructure bill after months of negotiation.
bipolaradjective	Relating to a mental health condition marked by alternating periods of depression and mania.	Her psychiatrist explained that bipolar disorder causes extreme shifts between low and elevated moods.
bipednoun	An animal that walks on two legs rather than four.	Humans are bipeds, while most other mammals move around on four legs.
bisectverb	To divide something into two equal or roughly equal parts.	A perpendicular line bisects the angle, creating two equal smaller angles.
bicentennialnoun	A two-hundredth anniversary, or the celebration marking it.	The town organized fireworks and parades for its bicentennial celebration.
biannualadjective	Happening twice a year.	The company holds biannual meetings each spring and autumn to review progress.
bifocaladjective	Having two parts with different focal lengths, especially in eyeglass lenses for near and far vision.	His bifocal glasses let him read a book and see across the room clearly.
bilateraladjective	Involving two parties or sides, especially in an agreement or negotiation.	The two countries signed a bilateral trade agreement reducing tariffs on both sides.
biathlonnoun	A winter sport combining cross-country skiing with rifle shooting.	She won a bronze medal in the biathlon at the winter Olympics.
bivalvenoun	A mollusk, such as a clam or oyster, with a shell made of two hinged parts.	The chef steamed a dozen bivalves and served them with garlic butter and bread.
biweeklyadjective	Happening every two weeks, or, less commonly, twice within a single week.	The newsletter is published biweekly, so subscribers receive a new issue every other Friday.
bicarbonatenoun	A chemical compound containing the bicarbonate ion, commonly known in its sodium form as baking soda.	She stirred bicarbonate of soda into the batter to help it rise.
bidirectionaladjective	Able to move, function, or transmit information in two opposite directions.	The new highway lane allows bidirectional traffic during rush hour.
biconvexadjective	Having two surfaces that curve outward on both sides, like a lens bulging on each face.	A magnifying glass typically uses a biconvex lens to focus light.
biconcaveadjective	Having two surfaces that curve inward on both sides, like a shallow bowl on each face.	Red blood cells have a biconcave shape that increases their surface area.

What does the prefix bi- mean?

Bi- comes from Latin and means two or twice. It shows up in everyday words like bicycle, which has two wheels, and bilingual, which refers to speaking two languages, as well as more specialized terms such as bipartisan, meaning involving two parties. Watch for words that only look like they start with bi- but come from a different root, such as bio- words like biology.

Frequently asked questions

What does the prefix bi- mean?

It means two or twice, as in bicycle, which has two wheels, or biweekly, which can mean every two weeks.

What is the difference between bi- and bio- words?

Bi- means two, as in bilingual, while bio- means life, as in biology; the two prefixes look similar but come from different roots.