Nama sandwicensis is an annual or perhaps a short-lived perennial herb that forms prostrate mats up to approximately 20 cm in diameter.  The stems are prostrate, freely branched, and densely hirsute. The leaves are simple and alternate with spatulate blades measuring 6–22(–55 in lowest leaves) mm long and 2–7 mm wide. They are densely hirsute with somewhat appressed hairs and are slightly thick. The margins are entire and strongly revolute, tapering gradually to the base. The leaves are sessile, with no stipules present. The flowers are either solitarily or in small cymes of 1–2 in the leaf axils, with pedicels measuring 2–5 mm long. The flowers are bisexual (perfect), actinomorphic (radially symmetric), or occasionally slightly irregular. The calyx lobes are narrowly oblong or occasionally narrowly oblong–spatulate, 4–4.5 mm long, enlarging up to approximately 6 mm long in fruit. The corolla is purplish blue, pink, or white, with a yellow throat. It features a tube approximately 5 mm long, which is pubescent externally and glabrous internally, often with scales at the summit opposite the lobes formed by the invagination of the corolla tube. The corolla lobes are spreading, approximately 2 mm long. The plant has five stamens inserted about 1 mm above the base of the corolla tube, with filaments of unequal length. The anthers are dithecal, opening by longitudinal slits. The ovary is superior, approximately 2 mm long, and 1-celled but appears 2-celled due to the strongly intruded placentas and puberulent. The style is divided nearly to the base, 1–2 mm long, and gynobasic, arising between the essentially distinct ovary lobes, sometimes terminal and often heterostylous. The stigma is usually simple, capitate or discoid, sometimes 2-lobed or 4-lobed. The fruit typically consists of (1–)4 1-seeded separate nutlets or 1–2 1–4-seeded nuts or drupelets; these are variously sculptured, pubescent or glabrous, and ± glossy. The capsules are loculicidal or rarely septicidal, membranous, and oblong–ovoid, approximately 3–4 mm long. The seeds are numerous, 20–60, yellowish brown, narrowly ellipsoid, approximately 0.5 mm long, and shallowly pitted. It is often found in sandy soils or on raised limestone reefs within strand and coastal vegetation and occasionally as a pioneer in dry shrubland between 0-220 meters.