inverse

a. [ L. inversus, p. p. of invertere: cf. F. inverse. See Invert. ] [ 1913 Webster ]

1. Opposite in order, relation, or effect; reversed; inverted; reciprocal; -- opposed to direct. [ 1913 Webster ]

2. (Bot.) Inverted; having a position or mode of attachment the reverse of that which is usual. [ 1913 Webster ]

3. (Math.) 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 or angle whose sine is x. [ 1913 Webster ]

Inverse figures (Geom.), two figures, such that each point of either figure is inverse to a corresponding point in the order figure. --
Inverse points (Geom.), two points lying on a line drawn from the center of a fixed circle or sphere, and so related that the product of their distances from the center of the circle or sphere is equal to the square of the radius. --
Inverse ratio, or
Reciprocal ratio (Math.), the ratio of the reciprocals of two quantities. --
Inverse proportion, or
Reciprocal proportion, an equality between a direct ratio and a reciprocal ratio; thus, 4 : 2 : : 1/3 : 1/6, or 4 : 2 : : 3 : 6, inversely. [ 1913 Webster ]

n. That which is inverse. [ 1913 Webster ]

Thus the course of human study is the inverse of the course of things in nature. Tatham. [ 1913 Webster ]