The Collaborative International Dictionary of English v.0.48:

Sig \Sig\, n. [Akin to AS. s[imac]gan to fall. [root]151a. See
   Sink, v. t.]
   Urine. [Prov. Eng.]
   [1913 Webster]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

SIG
       Special Interest Group


The Jargon File (version 4.4.7, 29 Dec 2003):

SIG
 /sig/, n.

    (also common as a prefix in combining forms) A Special Interest Group, in
    one of several technical areas, sponsored by the Association for Computing
    Machinery; well-known ones include SIGPLAN (the Special Interest Group on
    Programming Languages), SIGARCH (the Special Interest Group for Computer
    Architecture) and SIGGRAPH (the Special Interest Group for Computer
    Graphics). Hackers, not surprisingly, like to overextend this naming
    convention to less formal associations like SIGBEER (at ACM conferences)
    and SIGFOOD (at University of Illinois).


The Free On-line Dictionary of Computing (30 December 2018):

Sig

   Signal Processing, Analysis, and Display program.  An
   environment with an associated programming language by Jan
   Carter of Argonne National Lab.  Telephone +1 (312) 972
   7250.

   [Jargon File]


The Free On-line Dictionary of Computing (30 December 2018):

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)


The Free On-line Dictionary of Computing (30 December 2018):

Special Interest Group
SIG

   (SIG) One of several technical areas, sponsored by the
   Association for Computing Machinery.  Well-known SIGs
   include SIGPLAN (the Special Interest Group on Programming
   Languages), SIGARCH (the Special Interest Group for Computer
   Architecture) and SIGGRAPH (the Special Interest Group for
   Computer Graphics).

   (1994-10-27)