curl (v.) Look up curl at Dictionary.com
mid-15c., metathesis of crulle (c.1300), probably from an unrecorded Old English word or from Middle Dutch krul "curly," from Proto-Germanic *krusl- (cognates: East Frisian krull "lock of hair," Middle High German krol, Norwegian krull, Danish krølle "curl"). The noun is recorded from c.1600.