From Longman Dictionary of Contemporary Englishcockroachcock‧roach /ˈkɒk-rəʊtʃ $ ˈkɑːk-roʊtʃ/ (also roach American English) noun [countable] 
HBIa large black or brown insect that lives in dirty houses, especially if they are warm and there is food to eat
HBIa large black or brown insect that lives in dirty houses, especially if they are warm and there is food to eatExamples from the Corpus
cockroach• At a certain point, great big cockroaches no longer inspire that skin-crawling disgust.• Mira Sorvino stars in this dim-witted, dimly lit monster flick about gigantic cockroaches living in the New York subway system.• Some people are allergic to molds, dust mites, animal dander or cockroaches.• At playtime she opened the tin and let the cockroach fly into my blouse.• The fungi grows in just these sites in wild cockroaches.Origin cockroach (1600-1700) Spanish cucaracha, from cuca “caterpillar” 