areca nut
The seed of the areca palm, often chewed as a stimulant in parts of Asia. This is the botanical term.
See also: ビンロウジュ
Areca nut is used as an ingredient in chewing tobacco in Southeast Asia.
betel nut
Colloquial term for the areca nut, often used when referring to its use in betel quid. In everyday language, ビンロウジ is more common than the formal 檳榔子.
I bought betel nuts at the market.