English Dictionary

if and only if

conj

(logic, mathematics) Is equivalent to; implies and is implied by; is true and false in the same cases as. / (by extension, informal) If, with added intensity

If you study hard, then you will pass the exam.

意味（1）

(logic, mathematics) Is equivalent to; implies and is implied by; is true and false in the same cases as.

A rectangle is a square if and only if all four of its sides have the same length.

意味（2）

(by extension, informal) If, with added intensity