Comment: Vocalism is hard to establish (mainly because of the root's expressive nature). In Lezg., besides the adjective purp:u (cf. also Akht. p:ɨrp:ɨ) there exists an expressive suffixed formation: bub-uχ "cock's wattle"). The original meaning of the root must have been "soft, fluffy hair, down" (cf. the external evidence; note that in Ud. pop also means "goat's wool"). Since -r- is observed only in adjectival forms, it must be an adjectival infix here.