ناب

nāb (i.q. nāw, q.v.), s.m. Channel; canal; furrow, groove; fluting (of a pillar); moulding; cornice; frieze:—nāb-dār, adj. Grooved; fluted; indented:—nāb-dān, s.m. A drain, sewer, gutter; a canal; an aqueduct.