Comments: Seems to be less used in modern Kab. (in Ad. this is the main word for 'big'). PAK *čxʷa. The AK-Ub. comparison belongs to Dumézil (1932, 95). Klimov (1969, 290) has compared the AK root with Abkh. a-mcχʷ 'surplus'; this comparison is, however, justly rejected by Shagirov (2, 61-62) (both for phonetic and semantic reasons).
The precise nature of the initial PWC affricate here is hard to determine, since both in PAK and Ub. the initial clusters of the type 'affricate+fricative' are substantially restricted (in Ub. all affricates change to fricatives in this position; in PAK palatalized/non-palatalized affricates are neutralised before fricatives). Position within a cluster also explains the change of uvular to velar in PAK (no combinations of front affricates + uvular fricatives are allowed).