Scaevola glabra is a shrub that grows 1.5–4 meters tall, with primarily naked or leafless stems except for the distal portions. The leaves are simple, alternate, and tend to be crowded near the ends of the branches. The blades are oblanceolate or obovate, measuring 5–15 cm long and 2.5–5 cm wide, with an acute or acuminate apex and an acuminate base. They are glabrous and leathery, and their margins are either entire or toothed. The petioles are 1–3 cm long and feature axillary tufts of hairs. Stipules are absent. The flowers typically occur singly or rarely in pairs in the leaf axils and can be erect or pendulous with peduncles that are 10–30 mm long, with bracteoles. The flowers are bisexual (perfect) and strongly irregular. The calyx is 5-parted, 6–8 mm long, and about 5 mm wide, with narrowly lanceolate lobes 3–8 mm long and glabrous. The corolla is bright yellow, waxy, and curved outward, 5-parted with a tube 15–32 mm long, split adaxially from half to nearly its entire length, and the lobes are lanceolate, approximately 12 mm long with winged margins. It has five distinct stamens that are roughly as long as the corolla tube; the anthers are introrse, dithecal, and open by longitudinal slits, shedding pollen collected by the indusium on the outgrowing, downward curving style. The ovary is inferior, ovoid, 2-celled, with axile placentation, a 20–30 mm long style, and a 2-lobed stigma. The fruit is a drupaceous, dark purplish black, ovoid drupe, 10–14 mm long, 7–10 mm wide, and glabrous. The seeds are one to numerous, with oily endosperm. It occurs in very wet forests between 200-800 meters.