The Collaborative International Dictionary of English v.0.48:

Signature \Sig"na*ture\, v. t.
   To mark with, or as with, a signature or signatures.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Signature \Sig"na*ture\, n. [F. (cf. It. signatura, segnatura,
   Sp. & LL. signatura), from L. signare, signatum. See Sign,
   v. t.]
   1. A sign, stamp, or mark impressed, as by a seal.
      [1913 Webster]

            The brain, being well furnished with various traces,
            signatures, and images.               --I. Watts.
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            The natural and indelible signature of God, which
            human souls . . . are supposed to be stamped with.
                                                  --Bentley.
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   2. 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.
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   3. (Physiol.) An outward mark by which internal
      characteristics were supposed to be indicated.
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            Some plants bear a very evident signature of their
            nature and use.                       --Dr. H. More.
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   4. (Old Med.) 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.
      [1913 Webster]

   5. (Mus.) 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.
      [1913 Webster]

   6. (Print.)
      (a) 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.
      (b) The printed sheet so marked, or the form from which it
          is printed; as, to reprint one or more signatures.
          [1913 Webster]

   Note: Star signatures (as A*, 1*) are the same characters,
         with the addition of asterisks, used on the first pages
         of offcuts, as in 12mo sheets.
         [1913 Webster]

   7. (Pharm.) 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).
      [1913 Webster]

WordNet (r) 3.0 (2006):

signature
    n 1: your name written in your own handwriting
    2: a distinguishing style; "this room needs a woman's touch"
       [syn: touch, signature]
    3: a melody used to identify a performer or a dance band or
       radio/tv program [syn: signature, signature tune, theme
       song]
    4: the sharps or flats that follow the clef and indicate the key
       [syn: key signature, signature]
    5: a sheet with several pages printed on it; it folds to page
       size and is bound with other signatures to form a book

The Free On-line Dictionary of Computing (19 January 2023):

signature
sig

   1. A set of function symbols with arities.

   2.  (Or sig) A few lines of information about the
   sender of an electronic mail message or news posting.
   Most Unix mail and news software will automagically append
   a signature from a file called .signature in the user's home
   directory to outgoing mail and news.

   A signature should give your real name and your e-mail
   address since, though these appear in the headers of your
   messages, they may be munged by intervening software.  It is
   currently (1994) hip to include the URL of your home page
   on the web in your sig.

   The composition of one's sig can be quite an art form,
   including an ASCII logo or one's choice of witty sayings
   (see sig quote, fool file).  However, large sigs are a
   waste of bandwidth, and it has been observed that the size
   of one's sig block is usually inversely proportional to one's
   prestige on the net.

   See also doubled sig, sig virus.

   2.  A concept very similar to abstract base
   classes except that they have their own hierarchy and can
   be applied to compiled classes.  Signatures provide a means
   of separating subtyping and inheritance.  They are
   implemented in C++ as patches to GCC 2.5.2 by Gerald
   Baumgartner .

   (ftp://ftp.cs.purdue.edu/pub/gb/).

   (2001-01-05)