The Collaborative International Dictionary of English v.0.48:

Patch \Patch\ (p[a^]ch), v. t. [imp. & p. p. Patched
   (p[a^]cht); p. pr. & vb. n. Patching.]
   1. To mend by sewing on a piece or pieces of cloth, leather,
      or the like; as, to patch a coat.
      [1913 Webster]

   2. To mend with pieces; to repair with pieces festened on; to
      repair clumsily; as, to patch the roof of a house.
      [1913 Webster]

   3. To adorn, as the face, with a patch or patches.
      [1913 Webster]

            Ladies who patched both sides of their faces.
                                                  --Spectator.
      [1913 Webster]

   4. To make of pieces or patches; to repair as with patches;
      to arrange in a hasty or clumsy manner; -- generally with
      up; as, to patch up a truce. "If you'll patch a quarrel."
      --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Patch \Patch\, n. [OE. pacche; of uncertain origin, perh. for
   placche; cf. Prov. E. platch patch, LG. plakk, plakke.]
   1. A piece of cloth, or other suitable material, sewed or
      otherwise fixed upon a garment to repair or strengthen it,
      esp. upon an old garment to cover a hole.
      [1913 Webster]

            Patches set upon a little breach.     --Shak.
      [1913 Webster]

   2. Hence: A small piece of anything used to repair a breach;
      as, a patch on a kettle, a roof, etc.
      [1913 Webster]

   3. A small piece of black silk stuck on the face, or neck, to
      hide a defect, or to heighten beauty.
      [1913 Webster]

            Your black patches you wear variously. --Beau. & Fl.
      [1913 Webster]

   4. (Gun.) A piece of greased cloth or leather used as
      wrapping for a rifle ball, to make it fit the bore.
      [1913 Webster]

   5. Fig.: Anything regarded as a patch; a small piece of
      ground; a tract; a plot; as, scattered patches of trees or
      growing corn.
      [1913 Webster]

            Employed about this patch of ground.  --Bunyan.
      [1913 Webster]

   6. (Mil.) A block on the muzzle of a gun, to do away with the
      effect of dispart, in sighting.
      [1913 Webster]

   7. A paltry fellow; a rogue; a ninny; a fool. [Obs. or
      Colloq.] "Thou scurvy patch." --Shak.
      [1913 Webster]

   Patch ice, ice in overlapping pieces in the sea.

   Soft patch, a patch for covering a crack in a metallic
      vessel, as a steam boiler, consisting of soft material, as
      putty, covered and held in place by a plate bolted or
      riveted fast.
      [1913 Webster]

WordNet (r) 3.0 (2006):

patch
    n 1: a small contrasting part of something; "a bald spot"; "a
         leopard's spots"; "a patch of clouds"; "patches of thin
         ice"; "a fleck of red" [syn: spot, speckle, dapple,
         patch, fleck, maculation]
    2: a small area of ground covered by specific vegetation; "a
       bean plot"; "a cabbage patch"; "a briar patch" [syn: plot,
       plot of land, plot of ground, patch]
    3: a piece of cloth used as decoration or to mend or cover a
       hole
    4: a period of indeterminate length (usually short) marked by
       some action or condition; "he was here for a little while";
       "I need to rest for a piece"; "a spell of good weather"; "a
       patch of bad weather" [syn: while, piece, spell,
       patch]
    5: a short set of commands to correct a bug in a computer
       program
    6: a connection intended to be used for a limited time [syn:
       temporary hookup, patch]
    7: sewing that repairs a worn or torn hole (especially in a
       garment); "her stockings had several mends" [syn: mend,
       patch, darn]
    8: a protective cloth covering for an injured eye [syn:
       eyepatch, patch]
    9: a piece of soft material that covers and protects an injured
       part of the body [syn: bandage, patch]
    v 1: to join or unite the pieces of; "patch the skirt" [syn:
         patch, piece]
    2: provide with a patch; also used metaphorically; "The field
       was patched with snow"
    3: mend by putting a patch on; "patch a hole" [syn: patch,
       patch up]
    4: repair by adding pieces; "She pieced the china cup" [syn:
       piece, patch]

Moby Thesaurus II by Grady Ward, 1.0:

268 Moby Thesaurus words for "patch":
   Hershey bar, X ray, actinic ray, actinism, area, atomic beam,
   atomic ray, aviation badge, badge, bailiwick, bar, bat out, beam,
   beam of light, birthmark, blaze, blemish, block, bloodstain, blot,
   blotch, blur, botch, brand, bring to terms, bungle,
   bury the hatchet, caste mark, check, checkmark, chevron, chicken,
   chip, cicatrix, clearing, clos, close, cobble, come to terms,
   commission, condition, corn field, cover, croft, crumb,
   cultivated land, cut, dab, dapple, dappledness, dappleness, darn,
   dash off, daub, discoloration, do anyhow, do by halves,
   do carelessly, do offhand, do up, doctor, dot, dottedness, eagle,
   earmark, enclave, engraving, epaulet, episode, experience, eyesore,
   fake up, field, fix, fix up, fleck, flick, flyspeck, forty,
   freckle, freckliness, fudge up, gamma ray, gash, gleam, graving,
   ground, hack, hash mark, hayfield, heal, improvise, infrared ray,
   insignia of branch, interval, invisible radiation, jot, jury-rig,
   knock off, knock out, knock together, knock up, kraal, lash up,
   leam, lentigo, lot, macula, maculation, macule, mark, marking,
   mend, mole, morceau, morsel, mottle, mottledness, nevus, nick, nip,
   notch, oak leaf, organization insignia, overhaul, overseas bar,
   pad, paddy, pale, parachute badge, parcel, parcel of land,
   patch together, patch up, pencil, period, photon, piece,
   piece of land, pip, plat, plot, plot of ground, point, pointillage,
   pointillism, polka dot, pound out, prick, puncture,
   put in commission, put in order, put in repair, put in shape, quad,
   quadrangle, radiation, radiorays, ray, ray of light, ready,
   real estate, rebuild, recap, reconcile, recondition, reconstruct,
   reinforce, reinforcement, repair, resolve, responsibility, retread,
   revamp, ribbon, ribbon of light, rice paddy, rough out, roughcast,
   roughhew, scar, scarification, score, scotch, scrap, scratch,
   scratching, section, segment, service, service stripe, set right,
   set straight, set to rights, settle, sew up, shiver,
   shoulder patch, shoulder sleeve insignia, shred, slap up, sliver,
   smear, smirch, smithereen, smouch, smudge, smut, smutch, snick,
   snip, snippet, solar rays, spatter, speck, speckle, speckliness,
   spell, splash, splatter, splinter, splotch, spot, spottedness,
   spottiness, spread eagle, square, stage, stain, star, stigma,
   stipple, stippledness, stippling, stitch, straighten out,
   strawberry mark, streak, stream, stream of light, streamer, stripe,
   submarine badge, tag, taint, tarnish, tatter, tattoo, tattoo mark,
   territory, throw off, throw together, tick, time, tinker,
   tinker up, tittle, toss off, toss out, toss together, tract,
   trifle with, ultraviolet ray, vamp, violet ray, watermark,
   wheat field, whomp up



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

patch


    1. n. A temporary addition to a piece of code, usually as a 
    quick-and-dirty remedy to an existing bug or misfeature. A patch may or
    may not work, and may or may not eventually be incorporated permanently
    into the program. Distinguished from a diff or mod by the fact that a
    patch is generated by more primitive means than the rest of the program;
    the classical examples are instructions modified by using the front panel
    switches, and changes made directly to the binary executable of a program
    originally written in an HLL. Compare one-line fix.

    2. vt. To insert a patch into a piece of code.

    3. [in the Unix world] n. A diff (sense 2).

    4. A set of modifications to binaries to be applied by a patching program.
    IBM operating systems often receive updates to the operating system in the
    form of absolute hexadecimal patches. If you have modified your OS, you
    have to disassemble these back to the source. The patches might later be
    corrected by other patches on top of them (patches were said to ?grow scar
    tissue?). The result was often a convoluted patch space and headaches
    galore.

    5. [Unix] the patch(1) program, written by Larry Wall, which automatically
    applies a patch (sense 3) to a set of source code.

    There is a classic story of a tiger team penetrating a secure military
    computer that illustrates the danger inherent in binary patches (or,
    indeed, any patches that you can't ? or don't ? inspect and examine before
    installing). They couldn't find any trap doors or any way to penetrate
    security of IBM's OS, so they made a site visit to an IBM office (remember,
    these were official military types who were purportedly on official
    business), swiped some IBM stationery, and created a fake patch. The patch
    was actually the trapdoor they needed. The patch was distributed at about
    the right time for an IBM patch, had official stationery and all
    accompanying documentation, and was dutifully installed. The installation
    manager very shortly thereafter learned something about proper procedures.


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

patch

    1. A temporary addition to a piece of code, usually
   as a quick-and-dirty remedy to an existing bug or
   misfeature.  A patch may or may not work, and may or may not
   eventually be incorporated permanently into the program.
   Distinguished from a diff or mod by the fact that a patch
   is generated by more primitive means than the rest of the
   program; the classical examples are instructions modified by
   using the front panel switches, and changes made directly to
   the binary executable of a program originally written in an
   HLL.  Compare one-line fix.

   2. To insert a patch into a piece of code.

   3. [in the Unix world] A diff.

   4. A set of modifications to binaries to be applied by a
   patching program.  IBM systems often receive updates to the
   operating system in the form of absolute hexadecimal
   patches.  If you have modified your OS, you have to
   disassemble these back to the source code.  The patches
   might later be corrected by other patches on top of them
   (patches were said to "grow scar tissue").  The result was
   often a convoluted patch space and headaches galore.

   There is a classic story of a tiger team penetrating a
   secure military computer that illustrates the danger inherent
   in binary patches (or, indeed, any patches that you can't - or
   don't - inspect and examine before installing).  They couldn't
   find any trap doors or any way to penetrate security of
   IBM's OS, so they made a site visit to an IBM office
   (remember, these were official military types who were
   purportedly on official business), swiped some IBM stationery,
   and created a fake patch.  The patch was actually the trapdoor
   they needed.  The patch was distributed at about the right
   time for an IBM patch, had official stationery and all
   accompanying documentation, and was dutifully installed.  The
   installation manager very shortly thereafter learned something
   about proper procedures.

   5. Larry Wall's "patch" utility program, which
   automatically applies a patch to a set of source code or
   other text files.  Patch accepts input in any of the four
   forms output by the Unix diff utility.  When the files
   being patched are not identical to those on which the diffs
   were based, patch uses heuristics to determine how to
   proceed.

   Diff and patch are the standard way of producing and applying
   updates under Unix.  Both have been ported to other
   operating systems.

   Patch Home (http://gnu.org/software/patch/patch.html).

   [Jargon File]

   (2005-05-16)