Comment: Obl. base *č̣urä- (cf. Lezg. č̣ura-). 4th class in Rut. and Tsakh. The Kryz. word is somewhat dubious (both phonetically and semantically); cf. also Kryz. č̣erč̣ur 'swamp, marsh' (with the same reduplication as in Bud.).
The original meaning of this nominal stem may be reconstructed as "uncultivated land; waste land". It seems quite probable that it served as basis for the adjectival stem *č̣urɨ- (~-o-) with the basic meaning "wild": cf. Lezg. č̣uru "wild (of plants)"; Tab. č̣uru "wild (of plants); bad", substantivated in č̣uru-b "pus" (Düb. č̣iruv); Ag. Bursh. č̣ire-r "dirty, bad", Burk. č̣ure-f 'old, worn out' (probably > Darg. Chir. č̣ir-ze 'lean'); Kryz. č̣ir "wild (of plants, animals)", secondarily substantivated as č̣ir "wild pear"; possibly also Rut. č̣irɨ-dɨ "lame" ( < "crippled, bad").
Kryz. č̣erä 'cavern' is somewhat deviant both phonetically (-e-) and semantically. Perhaps it would be better to separate it and compare it to another root, reflected in PA *rič̣:o 'cavern' (And. reč̣:o, Akhv. rec̣:a, Cham. jeṣa, Gig. ruc̣a, Tind. ruč:a).