The Collaborative International Dictionary of English v.0.48:

Source \Source\, n. [OE. sours, OF. sourse, surse, sorse, F.
   source, fr. OF. sors, p. p. of OF. sordre, surdre, sourdre,
   to spring forth or up, F. sourdre, fr. L. surgere to lift or
   raise up, to spring up. See Surge, and cf. Souse to
   plunge or swoop as a bird upon its prey.]
   1. The act of rising; a rise; an ascent. [Obs.]
      [1913 Webster]

            Therefore right as an hawk upon a sours
            Up springeth into the air, right so prayers . . .
            Maken their sours to Goddes ears two. --Chaucer.
      [1913 Webster]

   2. The rising from the ground, or beginning, of a stream of
      water or the like; a spring; a fountain.
      [1913 Webster]

            Where as the Poo out of a welle small
            Taketh his firste springing and his sours.
                                                  --Chaucer.
      [1913 Webster]

            Kings that rule
            Behind the hidden sources of the Nile. --Addison.
      [1913 Webster]

   3. That from which anything comes forth, regarded as its
      cause or origin; the person from whom anything originates;
      first cause.
      [1913 Webster]

            This source of ideas every man has wholly in
            himself.                              --Locke.
      [1913 Webster]

            The source of Newton's light, of Bacon's sense.
                                                  --Pope.
      [1913 Webster]

   Syn: See Origin.
        [1913 Webster]

WordNet (r) 3.0 (2006):

source
    n 1: the place where something begins, where it springs into
         being; "the Italian beginning of the Renaissance"; "Jupiter
         was the origin of the radiation"; "Pittsburgh is the source
         of the Ohio River"; "communism's Russian root" [syn:
         beginning, origin, root, rootage, source]
    2: a document (or organization) from which information is
       obtained; "the reporter had two sources for the story"
    3: anything that provides inspiration for later work [syn:
       source, seed, germ]
    4: a facility where something is available
    5: a person who supplies information [syn: informant,
       source]
    6: someone who originates or causes or initiates something; "he
       was the generator of several complaints" [syn: generator,
       source, author]
    7: (technology) a process by which energy or a substance enters
       a system; "a heat source"; "a source of carbon dioxide" [ant:
       sink]
    8: anything (a person or animal or plant or substance) in which
       an infectious agent normally lives and multiplies; "an
       infectious agent depends on a reservoir for its survival"
       [syn: reservoir, source]
    9: a publication (or a passage from a publication) that is
       referred to; "he carried an armful of references back to his
       desk"; "he spent hours looking for the source of that
       quotation" [syn: reference, source]
    v 1: get (a product) from another country or business; "She
         sourced a supply of carpet"; "They are sourcing from
         smaller companies"
    2: specify the origin of; "The writer carefully sourced her
       report"

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "source":
   adviser, ambition, announcer, annunciator, antecedent, aspiration,
   author, authority, authorship, basis, begetter, beginning,
   birthplace, bonanza, calling, cause, channel, commencement,
   communicant, communicator, conception, consideration, cornucopia,
   creator, dawn, dawning, derivation, determinant, documentation,
   enlightener, expert witness, font, fount, fountain, fountainhead,
   genesis, goal, gold mine, gossipmonger, grapevine, grass roots,
   ground, guiding light, guiding star, head, headstream, headwater,
   headwaters, ideal, inception, informant, information center,
   information medium, informer, inspiration, intention, interviewee,
   lode, lodestar, mainspring, matter, mine, monitor, mother, motive,
   mouthpiece, newsmonger, notifier, onset, opening, origin, original,
   origination, originator, outset, parent, paternity, press,
   principle, provenance, provenience, public relations officer,
   publisher, quarry, radical, radio, radix, reason, reporter,
   resource, rise, rising, riverhead, root, roots, rootstock, sake,
   score, source of supply, spokesman, spring, staple, start,
   starting, stem, stock, taproot, television, teller, tipster, tout,
   ulterior motive, vein, vocation, well, wellhead, wellspring,
   whence, witness



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

source
 n.

    [very common] In reference to software, source is invariably shorthand for
    ?source code?, the preferred human-readable and human-modifiable form of
    the program. This is as opposed to object code, the derived binary
    executable form of a program. This shorthand readily takes derivative
    forms; one may speak of ?the sources of a system? or of ?having source?.


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

source code
source
source language

    (Or "source", or rarely "source language")
   The form in which a computer program (software) is written by
   the programmer.  Source code is written in some formal
   programming language which can be compiled automatically into
   object code or machine code or executed by an interpreter.

   Source code might be stored in a source code management system.

   If you have the source code for a program rather than just its
   compiled, executable form, then you can, with the right tools,
   modify it to fix bugs or add new features.  This is the basis
   of the open source philosophy - empowering people to improve the
   software they use for the benefit of themselves and others.

   The Jargon File would have us believe that an old-time hacker
   might refer to source code informally as "English", with the
   implication that to him his favourite programming language is at
   least as readable as English.

   (2014-06-27)