Quahaug

n. edible American round clam with hard shell

The hard clam or quahog, Mercenaria mercenaria is a bivalve mollusc native to the eastern shores of North America, from Prince Edward Island to the Yucatán Peninsula. Older sources may give it the systematic name Venus mercenaria. It is one of many unrelated bivalves referred to as clams.
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Noun
1. Atlantic coast round clams with hard shells; large clams usually used for chowders or other clam dishes
(synonym) quahog, hard-shell clam, round clam
(hypernym) clam
(hyponym) littleneck, littleneck clam
(part-holonym) quahog, hard-shell clam, round clam, Venus mercenaria, Mercenaria mercenaria
2. an edible American clam
(synonym) quahog, hard-shell clam, round clam, Venus mercenaria, Mercenaria mercenaria
(hypernym) clam
(hyponym) littleneck, littleneck clam
(member-holonym) Venus, genus Venus
(part-meronym) quahog, hard-shell clam, round clam

(n.)
An American market clam (Venus mercenaria). It is sold in large quantities, and is highly valued as food. Called also round clam, and hard clam.
  

Alantic Coast clam.