Sindarin 

tûm

deep valley

(under or among hills) tûm, tum- (i dûm, o thûm, construct tum), pl. tuim (i thuim)

tûm

deep valley

(under or among hills) tûm, tum- (i dûm, o thûm, construct tum), pl. tuim (i thuim). or

tûm

deep valley

tum- (i** dûm, o thûm, construct tum), pl. t**uim (i** thuim**)