The Collaborative International Dictionary of English v.0.48:

Roach \Roach\, n. (Zool.)
   A cockroach.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Roach \Roach\, n. [OE. rroche; cf. AS. reohha, D. rog, roch, G.
   roche, LG. ruche, Dan. rokke ray, Sw. rocka, and E. ray a
   fish.]
   1. (Zool.)
      (a) A European fresh-water fish of the Carp family
          (Leuciscus rutilus). It is silver-white, with a
          greenish back.
      (b) An American chub (Semotilus bullaris); the fallfish.
      (c) The redfin, or shiner.
          [1913 Webster]

   2. (Naut.) A convex curve or arch cut in the edge of a sail
      to prevent chafing, or to secure a better fit.
      [1913 Webster]

   As sound as a roach [roach perhaps being a corruption of a
      F. roche a rock], perfectly sound.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Roach \Roach\, v. t.
   1. To cause to arch.
      [1913 Webster]

   2. To cut off, as a horse's mane, so that the part left shall
      stand upright.
      [1913 Webster]

WordNet (r) 3.0 (2006):

roach
    n 1: a roll of hair brushed back from the forehead
    2: the butt of a marijuana cigarette
    3: street names for flunitrazepan [syn: R-2, Mexican valium,
       rophy, rope, roofy, roach, forget me drug,
       circle]
    4: any of numerous chiefly nocturnal insects; some are domestic
       pests [syn: cockroach, roach]
    5: European freshwater food fish having a greenish back [syn:
       roach, Rutilus rutilus]
    v 1: comb (hair) into a roach
    2: cut the mane off (a horse)

Moby Thesaurus II by Grady Ward, 1.0:

106 Moby Thesaurus words for "roach":
   DET, DMT, LSD, Mary Jane, STP, THC, acid, afterglow, afterimage,
   antidepressant, ataractic, balance, butt, butt end, candle ends,
   cat flea, chaff, chigoe, cockroach, crab, debris, detritus,
   diethyltryptamine, dimethyltryptamine, dog flea, end, fag end,
   filings, flea, fossil, gage, ganja, grass, grayback, hallucinogen,
   hash, hashish, hay, hemp, holdover, husks, jigger, joint, kava,
   leavings, leftovers, louse, marijuana, mescal, mescal bean,
   mescal button, mescaline, mind-altering drug, mind-blowing drug,
   mind-expanding drug, mite, morning glory seeds, nit, odds and ends,
   offscourings, orts, parasite, parings, peyote, pot, psilocin,
   psilocybin, psychedelic, psychic energizer, psychoactive drug,
   psychochemical, psychotomimetic, rags, red bug, reefer, refuse,
   relics, remainder, remains, remnant, residue, residuum, rest,
   rubbish, ruins, rump, sand flea, sawdust, scourings, scraps,
   shadow, shavings, stick, straw, stubble, stump, survival,
   sweepings, tea, trace, tranquilizer, vermin, vestige, waste, weed,
   weevil



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

roach
 vt.

    [Bell Labs] To destroy, esp. of a data structure. Hardware gets toasted
    or fried, software gets roached. Probably derived from '70s and '80s drug
    slang; marijuana smokers used ?roach? to refer to the unsmokable remnant of
    a joint, and to ?roach? a joint was therefore to destroy it.


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

roach

    A Bell Labs term meaning destroy, especially of a
   data structure.  Hardware gets toasted or fried, software
   gets roached.

   [Why?]

   [Jargon File]

   (1999-02-08)