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:
“My mom is bi, my dad was gay, my sister was in a polyamorous relationship and that was my growing up experience,” she said.
From Los Angeles Times ● Jun. 3, 2024
They’re the default, and then there’s one variable, that they’re gay, or bi.
From New York Times ● Aug. 4, 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
One of my favorite things is this notion of Yohaku no bi.
From Salon ● Mar. 26, 2023
Because if Caitlin’s unfazed by her enby friend’s pronouns, she’d probably be unfazed by me being bi.
From "Leah on the Offbeat" by Becky Albertalli
Running fully on their own, at scale, is not yet possible, "because there is not enough data," said Xinrui Bi of AgiBot.
From Barron's ● Jun. 18, 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
“I want to be frank with you, Bwana and Bi Bolaji.”
From "Beasts of Prey" by Ayana Gray
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
However, it said the risk is tilted toward fewer hikes as the BI increasingly relies on nonrate measures to support the rupiah, it said.
From The Wall Street Journal ● Jul. 27, 2026
Senior Deputy Gov. Destry Damayanti will take over as acting BI governor.
From The Wall Street Journal ● Jul. 27, 2026
Others, including at ING, think BI will hold steady after the off-cycle move.
From The Wall Street Journal ● Jun. 12, 2026
In Miss Beauchamp, for instance, the personality known as BI was made up almost entirely of the religious and ethical ideas which formed one side of the original self.
From Introduction to the Science of Sociology by Robert Ezra Park
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
From a systematic point of view these leaves indicate the origin of the water-parsnips from ordinary umbellifers, which generally have bi- and tripinnate leaves.
From Species and Varieties, Their Origin by Mutation by Hugo de Vries
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.
