(1):
(a.) 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.
(2):
(n.) That which is inverse.
(3):
(a.) Opposite in order, relation, or effect; reversed; inverted; reciprocal; - opposed to direct.
(4):
(a.) Inverted; having a position or mode of attachment the reverse of that which is usual.