Kalmar "rashin harshe" ba shi da ma'anar ƙamus. Koyaya, a cikin ilimin harshe, sashin harshe yawanci yana nufin wani yanki na harshe, kamar sautin murya, morpheme, kalma, jumla, jumla, ko jumla. Ana amfani da waɗannan raka'a don nazarin tsari da aikin harshe da yadda ake amfani da shi wajen sadarwa. Misali, sautin wayoyi su ne mafi ƙarancin raka'ar sauti a cikin harshe, yayin da jimloli su ne mafi girman ma'ana. Fahimtar waɗannan sassan harshe yana da mahimmanci wajen koyo da koyar da harshe.