A tall and rather slender tree, with a sparse and poorly spreading crown, these are the most noticeable features of the brown-ironwood. It is a big forest tree, growing up to 30 m tall in its natural habitat. It is a deciduous tree, with a whitish, smooth trunk and bark that becomes brittle, flaky and dark grey on older trees. One cannot miss a matured Homalium dentatum tree because of its size and, of course, its growth form. The branches grow horizontally, and young branches appear dark brown, with many conspicuous pale lenticels.

Brown-ironwood saplings are often confused with those of White Stinkwood (Celtis africana). Even through the two trees do not belong to the same family, the texture, look and arrangement of their leaves indeed does look similar. Homalium dentatum has alternating leaves with bluntly toothed margins. Young leaves are narrowly ovate, the apex is also extended, they have a papery feel and are bright green. They look different compared to adult and older leaves, which are larger, roundish, with an abrupt drip tip and a rounded base, leathery, pale to dark green, faintly glossy because of the soft hairs which can be felt rather than seen on the upper side, while the underside is paler. Old leaves are coppery.

Idlebelendlovu has small, very strongly scented flowers. The flowers are creamy-green and fluffy, borne in branched heads in summer, between December and May. They are followed by a brown, conical fruit capsule that stays on the tree through winter and sometimes into early spring.