How to say "variable" in Japanese
Choosing the right word
- 変数へんすうnounThe word for a variable in mathematics or programming — a quantity or symbol whose value can change or be assigned. This is what you want for the technical sense of 'variable'.
- 可変かへんna-adjective, no-adjectiveThe adjective sense: describing something as variable or changeable — able to be changed, adjusted, or controlled, as opposed to fixed. It applies to settings or features, not to a quantity in an equation.
- 未知数みちすうnounPrimarily means an unknown: a quantity whose value is not yet known, as in solving an equation. It overlaps with 変数 but stresses the unknown; figuratively it describes an unpredictable factor.
- 不定ふていno-adjective, na-adjectiveSeldom the word you want for 'variable': it really means unsettled or indefinite — something not yet fixed or decided, such as a date that has not been set, not something that varies.
Use 変数 for a variable in mathematics or programming, 可変 for things that can be changed or adjusted, 未知数 for an unknown quantity, and avoid 不定, which means indefinite or unsettled rather than variable.
Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only
Japanese equivalents
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