Colubrina oppositifolia is a tree that can reach heights of 5 to 13 meters. The leaves of this species are simple, with an arrangement that is opposite and decussate, meaning pairs of leaves alternate at 90 degrees between nodes. The blades are ovate to ovate–elliptic, measuring 6–12 cm in length and 3–7 cm in width, extending to about 20 cm in length and 8.5 cm in width in seedlings. The apex of the leaves is acute to short-acuminate, and their surfaces are glabrous, dull, and membranous. Notably, the lower surfaces feature two types of glands: small, submarginal, and blackish, and a peculiar gland-like proliferation in the axil of each secondary vein. The leaves have entire margins and are pinnately veined, with petioles measuring 1.4–3 cm in length, extending up to 4.5 cm in seedlings. Each pair of leaves has stipules that are connate into a lanceolate structure, which is darkly pigmented, 6–8 mm long, caducous, and leaves a prominent whitish scar upon falling off. The flowers are found in thyrses of 10–12, measuring 10–15 mm long, with peduncles 3–8 mm long and pedicels approximately 2–3 mm long, which elongate to 6–13 mm in fruit. The flowers are bisexual (perfect) and actinomorphic, featuring a calyx of 5 deltate sepals and a corolla of 5 petals, each about 1.5 mm long. The style is short and 3-lobed. The stamens, numbering five and opposite the petals, have distinct filaments that are adnate to the base of the petals, with anthers that open by longitudinal slits. The ovary is partly inferior, 3-celled, with one ovule per cell, basal and erect, and anatropous, accompanied by a 3-lobed style. The fruit is drupaceous, broadly subglobose, measuring 8–11 mm long, and known for its explosive dehiscence along the ventral, axile, and longitudinal sutures. The seeds are oblong–obovoid, 6–8 mm long, with a shallowly notched base and a thick, bony seed coat. It thrives in dry to mesic forests at elevations ranging from 240-920 meters.