adj fourfold; as, to make quadruple restitution; a quadruple alliance.
2. quadruple ·vi to be multiplied by four; to increase fourfold; to become four times as much.
3. quadruple ·vt to multiply by four; to increase fourfold; to double; to double twice.
4. quadruple ·noun four times the sum or number; a fourfold amount; as, to receive to quadruple of the amount in damages.