Inverse

Opposite in order, relation, or effect; reversed; inverted; reciprocal; -- opposed to direct.

Inverted; having a position or mode of attachment the reverse of that which is usual.

Opposite in nature and effect; -- said with reference to any two operations, which, when both are performed in succession upon any quantity, reproduce that quantity; as, multiplication is the inverse operation to division. The symbol of an inverse operation is the symbol of the direct operation with -1 as an index. Thus sin-1 x means the arc whose sine is x.

That which is inverse.

Relating to the operation that reverses the effect of another operation