From WordNet (r) 3.0 (2006) [wn]:
cockroach
n 1: any of numerous chiefly nocturnal insects; some are
domestic pests [syn: cockroach, roach]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Cockroach \Cock"roach\, n. [Sp. cucaracha.] (Zool.)
An orthopterous insect of the genus Blatta, and allied
genera.
[1913 Webster]
Note: The species are numerous, especially in hot countries.
Those most commonly infesting houses in Europe and
North America are Blatta orientalis, a large species
often called black beetle, and the Croton bug
(Blatta Germanica, formerly Ectobia Germanica),
also called the German cockroach.
[1913 Webster +PJC]