Pritchardia hillebrandii is a medium-sized palm with a slender trunk reaching heights of 6–7 meters. The simple, spirally arranged leaves are rigid and thick, with surfaces that range from glaucous to pale green. The lower surfaces bear a few scattered, pale-colored, minute scales. The petioles are very densely covered with a felted, ashy-silvery indumentum, which extends profusely from the underside of the petiole onto the blade and along the ridges of segment folds. The veins are parallel, and stipules are absent. The 60–100 cm-long inflorescences are about as long as or even shorter than the petioles. They consist of three distinct, loose panicles emerging from a slender, peduncular part. The rachillae are rigid and thickish. The prophyll and peduncular bracts are thin, chartaceous, and more or less fugaciously silvery lepidote, becoming glabrate with weathering. The flowers are bisexual (perfect) and sessile. The calyx is cupular, shallowly three-lobed, and prominently nerved or smooth when dry. The corolla comprises three petals that are basally adnate to the staminal filament tube to about the height of the calyx. The distinct petal lobes are valvate in bud, caducous as the flower expands, prominently pocketed and furrowed within, and prominently nerved when dry. The six stamens have flattened, thickish filaments that are connate at the base into a tube equaling or exceeding the calyx and surrounding the carpels, then separating into abruptly subulate structures that do not inflex at the apex. The anthers are erect in bud, dorsifixed, and spread-erect to versatile at anthesis, oblong in outline, bifid at the base nearly to the insertion point, and emarginate at the apex, with a narrow connective. The anther sacs dehisce laterally and longitudinally. The superior ovary consists of three carpels, with only one typically maturing. The carpels are basally coherent, and each contains a single ovule. The broad-based styles are connate above into a trigonous column that tapers into a shallowly trifid stigma. The ovules are anatropous, erect, and attached at the base of the placenta. The yellowish or reddish-brown, nearly black at maturity, fruit is globose, measuring 2–2.2 cm long and slightly wider than long. The apex retains the persistent sterile carpels and style and is marked by two pronounced ridges descending from the apex. The surface is highly polished at maturity. The endocarp (pictured) is very thin, woody, and brittle. The globose seeds measure 11–13 mm in diameter, are distinct from the endocarp except at the hilum, and have a shiny surface. The endosperm is homogeneous except for a shallow invagination of the seed coat below the raphe, with the embryo positioned laterally near the base opposite the raphe. It occurs on cliffs in mesic to wet areas along the windward coast of Moloka’i between 30-600 meters.