bi
adjective
bi
1 American
[bahy]
/ baɪ /
adjective
-
bis,
plural
-
bi's
plural
Bi
2
American
Symbol, Chemistry.
BI
3
American
bi-
4
American
bi-
5
American
bi-
1
British
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
2
British
symbol
bi
3
British
/ baɪ /
adjective
bi-
4
British
combining form
bi
5
British
abbreviation
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; see twice
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
His interpretation of pansexuality is that "pan means being able to be attracted to anyone who identifies as gay, straight, bi, transsexual or non-binary."
From Salon ● Aug. 8, 2023
“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
I always thought that I wasn’t bi “enough” to identify that way, but on the apps, I was having what I’ve been told is a typical bisexual experience.
From Los Angeles Times ● Jan. 27, 2023
Everyone should have to declare one way or another, and it should be this big awkward thing whether you're straight, gay, bi, or whatever.
From "Simon vs. the Homo Sapiens Agenda" by Becky Albertalli
"In several hundred years, this is the first time the water has reached the second floor... Never before in history," said another resident, Bi Yunchun.
From Barron's ● Jul. 9, 2026
Other high-profile titles from international festivals include Luca Guadagnino’s campus drama “After the Hunt,” Kleber Mendonça Filho’s political thriller “The Secret Agent,” Bi Gan’s trippy drama “Resurrection” and Radu Jude’s updated “Dracula.”
From Los Angeles Times ● Sep. 23, 2025
One of the men, Theodore Bi, called the work “an idea anyone can get behind” and said they had intended to give it as a gift to Elon Musk.
From New York Times ● Nov. 20, 2024
The Pantastic Bi-Mo Bi-Bar Pride 2024: Join the Seattle Pan Bi Alliance this Pride month for this bimonthly Pantastic Bi-Mo Bi-Bar to meet up with other bi/pan+ folks for drinks and conversation.
From Seattle Times ● May 31, 2024
“Bwana and Bi Bolaji, thank you for coming so quickly.”
From "Beasts of Prey" by Ayana Gray
However, inflation is expected to remain within Bank Indonesia’s target range, which could allow BI to keep its focus on exchange-rate stability rather than respond to inflation, she added.
From The Wall Street Journal ● Sep. 25, 2026
One economist forecasts BI to raise the policy rate by 25 bp to 6.0%.
From The Wall Street Journal ● Sep. 22, 2026
Having a seasoned BI official at the helm would also signal the government’s preference for a technocratic, market-oriented transition, DBS economists Taimur Baig and Chua Han Teng said in a recent note.
From The Wall Street Journal ● Aug. 19, 2026
Wednesday’s meeting is under particular scrutiny as the BI undergoes a leadership transition following the departure of long-serving Gov. Perry Warjiyo, who stepped down in July citing personal reasons.
From The Wall Street Journal ● Aug. 19, 2026
For example, the "Make Money Fast" pyramid scheme exceeded a BI of 20 a long time ago, and is now considered "cancel on sight".
From The Jargon File, Version 4.2.2, 20 Aug 2000 by Guy L. Steele
Many were taking selfies with a three-metre-tall Unitree GD01, a towering rideable robot the firm says can switch between bi- and quadruped settings.
From Barron's ● Aug. 19, 2026
Two replication forks are formed at the origin of replication and these get extended bi- directionally as replication proceeds.
From Textbooks ● Jun. 9, 2022
Kids who grow up bi- or even trilingual may appear delayed in any one language, simply because they’re splitting the number of words they know between languages.
From Slate ● Nov. 14, 2019
“I don’t know, bi- or pansexual,” Katie said.
From New York Times ● May 24, 2018
Foliolate, having leaflets; the number indicated by the Latin prefixes, bi-, tri-, etc.
From The Wild Flowers of California: Their Names, Haunts, and Habits by Mary Elizabeth Parsons
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
