A sign, stamp, or mark impressed, as by a seal.

Especially, the name of any person, written with his
own hand, employed to signify that the writing which precedes accords
with his wishes or intentions; a sign manual; an autograph.

An outward mark by which internal characteristics
were supposed to be indicated.

A resemblance between the external characters of a
disease and those of some physical agent, for instance, that existing
between the red skin of scarlet fever and a red cloth; – supposed to
indicate this agent in the treatment of the disease.

The designation of the key (when not C major, or its
relative, A minor) by means of one or more sharps or flats at the
beginning of the staff, immediately after the clef, affecting all notes
of the same letter throughout the piece or movement. Each minor key has
the same signature as its relative major.

A letter or figure placed at the bottom of the first
page of each sheet of a book or pamphlet, as a direction to the binder
in arranging and folding the sheets.

The printed sheet so marked, or the form from which
it is printed; as, to reprint one or more signatures.

That part of a prescription which contains the
directions to the patient. It is usually prefaced by S or Sig. (an
abbreviation for the Latin signa, imperative of signare to sign or
mark).

To mark with, or as with, a signature or signatures.