Definition of Portuguese oyster in English:

Portuguese oyster

noun

  • A large edible oyster, Crassostrea angulata (now thought to be a variety of the Pacific oyster, C. gigas), which has a thick, white to pale brown shell with an irregular pattern of ridges and grooves, and was introduced to cultivation in Europe via Portugal.

Origin

Late 19th century; earliest use found in American Naturalist.