In logic and mathematics, a statement that is true when two conditions are both true or both false, often expressed as 'if and only if'; can be a noun or adjective.
From 'bi-' (two) plus 'conditional' (from Latin 'conditio' meaning a stipulation or requirement). This logical term emerged in formal logic and mathematics.
Biconditional statements are the mathematical equivalent of perfect symmetry—'you can vote if and only if you're 18 years old' means the same thing backwards and forwards, which is why mathematicians love them for defining exact boundaries.
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