In"dex , n. The ratio, or
formula expressing the ratio, of one
dimension of a thing to another dimension; as, the vertical index of the cranium.
In"dex (?), v. t. [imp. & p. p. Indexed (?);
p. pr. & vb. n.
Indexing.]
To provide with an index or table of references; to put into an index; as,
to index a book, or its contents.
In"dex (?), n.;
pl. E. Indexes (#), L. Indices
(#)(&?;). [L.: cf. F. index. See Indicate, Diction.]
1. That which points out; that which shows, indicates, manifests, or discloses.
Tastes are the indexes of the different qualities of
plants.
Arbuthnot. 2. That which guides, points out, informs, or directs; a pointer or
a hand that
directs to anything, as the hand of a watch, a movable finger on a gauge, scale, or other graduated instrument.
In printing, a sign [&fist;]
used to direct particular attention to a note or paragraph; -- called also fist.
3. A table for facilitating reference to topics, names, and the like,
in a book; --
usually alphabetical in arrangement, and printed at the end of the volume.
4. A prologue indicating what follows. [Obs.] Shak.
5. (Anat.) The second digit, that next to
the pollex, in the manus,
or hand; the
forefinger; index finger.
6. (Math.) The figure or letter which shows the power or
root of a quantity; the exponent. [In this sense the plural is
always indices.]
Index error, the error in
the reading of a mathematical instrument arising from the zero of the index not
being in complete adjustment with that of
the limb, or
with its theoretically perfect position in the instrument; a correction to be applied to the
instrument readings equal to the
error of the zero adjustment. -- Index expurgatorius. [L.] See Index prohibitorius (below). -- Index finger. See Index, 5. -- Index
glass, the mirror on the
index of a quadrant, sextant,
etc. -- Index hand, the pointer or hand of a clock, watch, or other registering machine; a hand that
points to something. --
Index of a
logarithm (Math.), the integral part of the logarithm, and always one less than the
number of integral figures in the given number. It is
also called the characteristic. -- Index of refraction, or Refractive index
(Opt.), the number
which expresses the ratio of the
sine of the
angle of incidence to the sine of the angle of
refraction. Thus the index of refraction for sulphur is 2, because, when light passes out of air into sulphur, the sine of the angle of
incidence is double the sine of the angle of refraction. -- Index plate, a graduated circular plate, or one with circular rows of holes differently spaced; used in
machines for graduating circles, cutting gear teeth, etc. -- Index
prohibitorius [L.], or Prohibitory index
(R. C. Ch.), a catalogue of books which are forbidden by the church
to be read;
the index expurgatorius
[L.], or expurgatory index, is a catalogue of books from which passages marked as against faith or morals must be removed before Catholics can read them. These catalogues are published with additions, from time to time,
by the Congregation of the Index, composed of cardinals,
theologians, etc., under the sanction of the pope. Hook. -- Index rerum
[L.], a tabulated and alphabetized notebook, for systematic preservation of items,
quotations, etc.
Hear it pronounced