September is Etymology Month (27)

creep O.E. creopan "to creep" (class II strong verb; past tense creap, pp. cropen), from P.Gmc. *kreupanan (cf. O.Fris. kriapa, M.Du. crupen, O.N. krjupa "to creep"), from PIE root *greug-. As a noun, "a creeping motion," from 1818; meaning "despicable person" is 1935, Amer.Eng. slang, perhaps from earlier sense of "sneak thief" (1914). Creeper "a gilded rascal" is recorded from c.1600, and the word also was used of certain classes of thieves, especially those who robbed customers in brothels. The creeps first attested 1849, in Dickens.