Comment: Cf. also Lezg. Kur. t:urḳun, Khl. tuḳun, Akht. ṭuḳun, Yark. durgun, Tab. Kand. gurǯim ( < *gurdim), Ag. Bursh. ḳulṭum, Burk. guṭaj, Arch. pl. gʷat:-ur. 3d class in all class-distinguishing languages.
The languages reveal suffixed forms with *-n (Lezg., Rut., Tsakh., Kryz., Bud.), *-m (Tab., Ag.), *-l,*-j (Ag.). The primary structure of laryngeal features (*k:ʷɨrṭ-) is probably retained in Ag. (guṭ-ul,guṭ-aj) and Lezg. Kur. (with metathesis t:urḳ-un). Forms in other languages and dialects have underwent a progressive or regressive assimilation (rather typical for roots of this structure). The vocalism is quite regular (Arch. and Kryz. -a- and -u- in other languages unambiguously point to *-ɨ- aftera labiovelar).
The resemblance to Pers. gurde 'kidney' (see Horn 1893, 202 for its Indo-Iranian etymology) is quite fortuitous (although Ud. gurdak: 'kidney' is obviously borrowed from Middle Persian and not related to other Lezghian forms): the loan is improbable both for phonetic reasons and because of the root's reliable EC etymology.