bi

¹ American  

[bahy] / baɪ /

adjective

plural

bis, bi's

1. Slang. bisexual.

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Bi ² American  

Symbol, Chemistry.

1. bismuth.

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BI ³ American  

abbreviation

plural

BI's

1. built-in.

2. business intelligence.

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bi- ⁴ American  

1. a combining form meaning “twice,” “two,” used in the formation of compound words.

   bifacial; bifarious.

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bi- ⁵ American  

1. variant of bio-, especially before a vowel.

   biopsy.

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bi- ¹ British  

combining form

1. two; having two

   bifocal

2. occurring every two; lasting for two

   biennial

3. on both sides, surfaces, directions, etc

   bilateral

4. occurring twice during

   biweekly

5. 1. denoting an organic compound containing two identical cyclic hydrocarbon systems

      biphenyl

   2. (rare in technical usage) indicating an acid salt of a dibasic acid

      sodium bicarbonate

   3. (not in technical usage) equivalent of di- 1

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Bi ² British  

symbol

1. bismuth

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bi ³ British  

/ baɪ /

adjective

1. slang short for bisexual bisexual

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bi- ⁴ British  

combining form

1. a variant of bio-

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bi ⁵ British  

abbreviation

1. Burundi

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Usage

What does bi- mean? Bi- is a combining form used like a prefix, and it means “two” or “twice.” It is often used in scientific terms, but it crops up in everyday language as well.Bi- comes from Latin bis, meaning “twice, doubly.” The Greek equivalent of this combining form is di-, as in diacid.What are variants of bi-?Bi- is related to the combining form bin- and is used with some words or word elements beginning with vowels. These two forms have similar origins, and for that reason, the difference between the two is a small yet important nuance: bi- often means “twice,” while bin- typically means “double.”Want to know more? Read our Words That Use bin- article.

Commonly Confused

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 ).

Etymology

Origin of bi¹

By shortening

Origin of bi-⁴

< Latin, combining form of bis; twice

Example Sentences

“I talked to a lot of people who identify as bi and they were like, ‘Thank you.’

From Los Angeles Times • Sep. 12, 2024

“Telling someone you’re gay or bi or part of the queer community, there’s a thing where you feel like they might see you differently or think that it would change who you are,” he said.

From New York Times • Jul. 29, 2023

I lived on Capitol Hill, I was a bi woman surrounded by gay men and a few women, who were most of my community.

From Seattle Times • Jun. 1, 2023

"We've got a lot of work to do to make sure that bi people feel safe, sharing who they are with us and being out in their day-to-day lives."

From BBC • Oct. 5, 2022

“It’s fine if you say it, Jupiter. I’m bi, too. It’s nothing to be ashamed of.”

From "Odd One Out" by Nic Stone