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. [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]The Collaborative International Dictionary of English v.0.48:

Proportion \Pro*por"tion\, n. [F., fr. L. proportio; pro before + portio part or share. See Portion.] [1913 Webster] 1. The relation or adaptation of one portion to another, or to the whole, as respect magnitude, quantity, or degree; comparative relation; ratio; as, the proportion of the parts of a building, or of the body. [1913 Webster] The image of Christ, made after his own proportion. --Ridley. [1913 Webster] Formed in the best proportions of her sex. --Sir W. Scott. [1913 Webster] Documents are authentic and facts are true precisely in proportion to the support which they afford to his theory. --Macaulay. [1913 Webster] 2. Harmonic relation between parts, or between different things of the same kind; symmetrical arrangement or adjustment; symmetry; as, to be out of proportion. "Let us prophesy according to the proportion of faith." --Rom. xii. 6. [1913 Webster] 3. The portion one receives when a whole is distributed by a rule or principle; equal or proper share; lot. [1913 Webster] Let the women . . . do the same things in their proportions and capacities. --Jer. Taylor. [1913 Webster] 4. A part considered comparatively; a share. [1913 Webster] 5. (Math.) (a) The equality or similarity of ratios, especially of geometrical ratios; or a relation among quantities such that the quotient of the first divided by the second is equal to that of the third divided by the fourth; -- called also geometrical proportion, in distinction from arithmetical proportion, or that in which the difference of the first and second is equal to the difference of the third and fourth. [1913 Webster] Note: Proportion in the mathematical sense differs from ratio. Ratio is the relation of two quantities of the same kind, as the ratio of 5 to 10, or the ratio of 8 to 16. Proportion is the sameness or likeness of two such relations. Thus, 5 to 10 as 8 to 16; that is, 5 bears the same relation to 10 as 8 does to 16. Hence, such numbers are said to be in proportion. Proportion is expressed by symbols thus: [1913 Webster] a:b::c:d, or a:b = c:d, or a/b = c/d. [1913 Webster] (b) The rule of three, in arithmetic, in which the three given terms, together with the one sought, are proportional. [1913 Webster] Continued proportion, Inverse proportion, etc. See under Continued, Inverse, etc. Harmonical proportion or Musical proportion, a relation of three or four quantities, such that the first is to the last as the difference between the first two is to the difference between the last two; thus, 2, 3, 6, are in harmonical proportion; for 2 is to 6 as 1 to 3. Thus, 24, 16, 12, 9, are harmonical, for 24:9::8:3. In proportion, according as; to the degree that. "In proportion as they are metaphysically true, they are morally and politically false." --Burke. [1913 Webster]