Pro*por"tion (?), n. [F., fr. L.
proportio; pro before + portio part or share. See
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.
The image of Christ, made after his own
Formed in the best proportions of her
sex. Sir W. Scott.
Documents are authentic and facts are true precisely in
proportion to the support which they afford to his
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.
3. The portion one receives when a whole is
distributed by a rule or principle; equal or proper share;
Let the women . . . do the same things in their
proportions and capacities. Jer.
4. A part considered comparatively; a
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
☞ 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:
a:b::c:d, or a:b = c:d, or a/b =
(b) The rule of three, in arithmetic, in which
the three given terms, together with the one sought, are
Continued proportion, Inverse
proportion, etc. See under Continued,
Inverse, etc. -- Harmonical, 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."