Definition of rice grain in US English:

rice grain

noun

  • 1An individual seed of rice, especially after removal of the husk. Also (as a mass noun): rice as a food grain.

  • 2Astronomy. A small, luminous, and short-lived patch on the surface of the sun; = "facula". Also called willow leaf. Now rare.

Origin

Mid 18th century; earliest use found in The Annual Register. From rice + grain.

Pronunciation

rice grain

/ˈrʌɪs ˌɡreɪn/