roach

Etymology 1

From Middle English roche, from Old French roche, from Middle Low German roche, ruche (“ray (fish)”), from Old Saxon *rūh, possibly from Proto-Germanic *rūhaz (“rough”). Cognate with Old English ruhha ("a ray"; > Middle English rouhe, rohȝe), German Rochen (“ray (fish)”).

noun

1. Certain members of the fish family Cyprinidae, including:
   1. Species in the genus Rutilus, especially:
      1. The common roach (Rutilus rutilus)
   2. The California roach, of the monotypic genus Hesperoleucus

Etymology 2

Back-formation from cockroach, as if it were a compound.

noun

1. (US) A cockroach.

Etymology 3

Apparently from extended or figurative use of roach (“Cyprinidae”), above. Compare the adjective roached (“styled so that the mane stands up from the neck”).

noun

1. (nautical) An extra curve of material added to the leech (aft edge) of a sail to increase the sail area.
2. A kind of headdress worn by some of the indigenous peoples of North America.

Etymology 4

Extended or jocular use of roach (“cockroach”), above. Attested since the 1930s.

noun

1. (US, slang, smoking) A marijuana cigarette, blunt, or joint.
   In his half hour of free time between brooms it was Willie's custom to smoke his lunch in an alleyway. He'd take just half a roach, only enough to make him feel a new day was starting, no more no less. 1957, Alfred Maund, The Big Boxcar, Urbana: University of Illinois Press, page 106
2. (US, slang, smoking) The butt of a marijuana cigarette.
3. (UK, slang, smoking) The filter of a rolled cigarette or joint, made from card or paper.

Etymology 5

Variant of roche (“rock”). Attested since the seventeenth century.

noun

1. (UK, obsolete, mining) A bed or stratum of some mineral.
   After long Working of this Coal, it was found upon the rising Grounds, that there lay another Roach of Coal, at the Depth of 14 Yards under it 1749, Rog. Mostyn, “Mineralogy”, in Philosophical Transactions and Collections to the End of the Year, volume II, London: Royal Society, →OCLC, page 379
2. (UK, regional) Gritty or coarse rock; especially Portland stone or similar limestone.
   The roach, both of the top and bottom beds, is always imperceptibly incorporated with the freestone, which is invariable situated beneath it. 1841, C.H. Smith, “Lithology; or Observations on Stone for Building”, in The Surveyor, Engineer, and Architect, →OCLC, page 13

Etymology 6

verb

1. (transitive) To cut or shave off the mane of a horse so that the remaining hair stands up on the neck.
2. (transitive, by extension) To cut a person's hair so that it stands straight up.