**The Collaborative International Dictionary of English v.0.48:**

Inverse \In*verse"\, 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.
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2. (Bot.) Inverted; having a position or mode of attachment
the reverse of that which is usual.
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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]