The verbal root as such is attested only in PGB (probably with a metathesis: *hɔʔɔ- < ʔɔhɔ- ). There are, however, better attested archaic nominal derivates: 1) PTs *ʁ:ʷǝ̃bu A, *ʁ:ʷǝ̃bǝr A : PTsKh *ʁǝ̃bu, *ʁǝ̃bǝR > Gin. ʁemer / ʁeme 'mill; wheel' (Lomtadze records also a variant ʁIemer), Khvarsh. ʁabo 'mill, millstone', ʁabal 'wheel', Inkh. ʁobol 'mill'; PGB *hɔbu, *hɔbǝr > Bezht. haboj 'mill' (Khosh. habo 'mill', habor 'blades of the mill-wheel', Tlad. habor 'mill; wheel'), Gunz. hɔbur 'mill'.
2) PTs *ʔaʁ:ʷǝ, *ʔaʁ:ʷǝr, reflected in Tsez. aʁur 'mill, millstone' (in dialects: Asakh. aʁʷir id., Kid. ʕaʁIu / aʁIu 'mill', ʕaʁIur 'mill-wheel, wheel').