1. A logical statement that is true when both parts have the same truth value; a compound proposition of the form 'if and only if' (often written as ↔ or ≡).
Usage: formal logic and mathematics; plural of biconditional

Examples

• In logic class, we studied biconditionals like 'A triangle is equilateral if and only if all its sides are equal.'
• The biconditionals in this proof show that the two conditions are logically equivalent.
• A statement and its contrapositive are biconditionals in classical logic.
• We use biconditionals to express necessary and sufficient conditions.
• The truth table for biconditionals shows they are true when both propositions match.