Eucalyptus arcana is a low, straggly tree, sometimes with several stems, that typically grows to high. It has rough, fibrous, grey to grey-brown bark from the base of the trunk to the larger branches, and smooth, grey to cream bark on the thinnest branches. Young plants and
coppice regrowth have four-sided stems and glossy elliptic to egg-shaped leaves long and wide with wavy edges. Adult leaves are lance-shaped, the same glossy green on both sides, with a blade that is long and wide on a
petiole long. The flowers buds are arranged in groups of seven on a
peduncle long, the individual flowers on a
pedicel up to long. Mature buds are oval to spindle-shaped, long and wide with an
operculum that is shaped like a blunt cone, about equal in length to the
floral cup. Flowering occurs in February and the flowers are white. The fruit are hemispherical to cone-shaped, long and wide containing dark brown to black ovoid seeds. ==Taxonomy and naming==