COMMENT: A rather widely represented common NC root. The etymology on the whole seems quite satisfactory, but there are some irregularities: in PD we would rather expect *z, not *c:. We may think that the root consonant here was expressively geminated (PD *ʔizz- > *ʔicc:-), and indeed we see traces of this gemination in Ak. izz-es,izz-ala. It is even possible that the gemination occurred as early as in Proto-Darg.-Lezg. - cf. a quite analogous gemination in Rut. =ädda- (normally -d- would be expected).
Cf. also Hurr. azz-u/ošχǝ 'tabooed, impure, sinful, sick (or the like)', see Diakonoff-Starostin 1986, 40.