boolean

IPA/ˈbuːliən/
KK[bulˈiən]IPA/ˈbuːliən/

boolean — adjective

  • booleanpositive
  • more booleancomparative
  • most booleansuperlative

1. describing a kind of logic, used heavily in computers and search engines, where

1.adjectiveC1
Definition

describing a kind of logic, used heavily in computers and search engines, where every value is either true or false (often written as 1 or 0) and where pieces of information are joined using AND, OR, or NOT.

Example

In Python, the variable is_open holds a Boolean value, so it is either True or False.

common compound: Boolean value

Yumi used a Boolean search to find papers that mention 'climate' AND 'rice' but NOT 'wheat'.

common compound: Boolean search

Common collocations
  • Boolean value
  • Boolean expression
  • Boolean operator
  • Boolean search
  • Boolean logic
  • Boolean algebra
  • Boolean variable
  • Boolean function
Synonyms
  • binary

    broader; describes anything with two states, not necessarily logical (binary code, binary star)

  • logical

    much wider; about reasoning in general, not the specific true/false system

  • two-valued

    technical, mostly in mathematical logic textbooks

Antonyms
  • fuzzy

    in logic, the opposite system: values can be anywhere between 0 and 1, not strictly true or false

Grammar Patterns

Boolean + noun (logic, value, expression, operator, search, algebra)

Usage Note

Almost always used directly before a noun (Boolean value, expression, operator, search, algebra, logic). Capitalised in formal writing because it comes from a person's name (George Boole), but lower-case 'boolean' is now standard in programming code (e.g. 'boolean isReady;' in Java).

Common Mistakes

The answer was very Boolean.
The answer was a simple yes or no.
Boolean is not a degree word; it describes a type of value, not how strongly something is true.
a Boolean number between 0 and 9
a Boolean value, either 0 or 1
Boolean values have only two possibilities, not a range.

Word family

  • Booleans
    nounC1

Synonym discussion

Sense: adjective/1

These four overlap in the world of logic and computing but pick out different ideas. 'Boolean' is the most specific: a system in which every value is exactly true or false, combined using AND, OR, and NOT. 'Binary' is broader — it just means 'having two states or symbols': binary code (0s and 1s), binary star (two stars orbiting), even binary opposition in literary theory. So all Boolean values are binary, but not all binary things are Boolean. 'Logical' is much wider still, covering any kind of valid reasoning, not just two-valued reasoning. 'Fuzzy' deliberately contrasts with Boolean: in fuzzy logic a statement can be 0.7 true, useful for things like washing-machine sensors that judge how dirty the water is. Programmers say 'Boolean variable'; astronomers say 'binary star'; philosophers say 'logical argument'; engineers say 'fuzzy controller'.

Boolean ↗binary ↗logical ↗fuzzy ↗

Common collocations

Nouns

Phrases

  • Boolean value
  • Boolean operator
  • Boolean expression
  • Boolean search

Etymology

English (proper noun)English

Named after the English mathematician George Boole (1815-1864), who in his 1854 book 'An Investigation of the Laws of Thought' worked out a way to write logical reasoning as algebra. In the early 20th century, Claude Shannon showed that Boole's two-valued algebra fit electric switches perfectly, which is why the word now lives mainly in computing.