1. [n]  European freshwater food fish having a greenish back
2. [n]  any of numerous chiefly nocturnal insects; some are domestic pests
3. [n]  the butt of a marijuana cigarette

1. \Roach\, n. (Zo["o]l.)
   A cockroach.
   
   

2. \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. (Zo["o]l.)
      (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.
   
   2. (Naut.) A convex curve or arch cut in the edge of a sail
      to prevent chafing, or to secure a better fit.
   
   {As sound as a roach} [roach perhaps being a corruption of a
      F. roche a rock], perfectly sound.
   
   

3. \Roach\, v. t.
   1. To cause to arch.
   
   2. To cut off, as a horse's mane, so that the part left shall
      stand upright.
   
   

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

[jargon file]