It is an evergreen tree growing to a height of 12–20 m. The leaves are alternate, 10–30 cm long, pinnate, with three to 11 leaflets, each leaflet 5–15 cm wide and 3–10 cm broad, with an entire margin. The flowers are small, 2.5–5 mm, apetalous, discoidal and borne in erect terminal panicles 15–30 cm wide. Rambutan trees can be male (producing only staminate flowers and, hence, produce no fruit), female (producing flowers that are only functionally female) or hermaphroditic (producing flowers that are female with a small percentage of male flowers). The fruit is a round to oval single-seeded drupe, 3–6 cm (rarely to 8 cm) long and 3–4 cm broad, borne in a loose pendant cluster of 10–20 together. The leathery skin is reddish (rarely orange or yellow) and covered with fleshy pliable spines, hence the name, which means 'hairs'. The spines (also known as "spinterns") contribute to the transpiration of the fruit, which can affect the fruit's quality. The fruit flesh, the aril, is translucent, whitish or very pale pink, with a sweet, mildly acidic flavor reminiscent of grapes. The single seed is glossy brown, 1–1.3 cm, with a white basal scar. Soft and containing equal portions of saturated and unsaturated fats, the seeds may be cooked and eaten. The peeled fruits can be eaten raw or cooked and eaten: first, the grape-like fleshy aril, then the nutty seed, with no waste.
