Definitions:

1. A long, smooth-shelled, burrowing clam found on Atlantic and Pacific beaches, often collected for food. NOUN
   • In some coastal communities, jackknife clams are a delicacy and are collected by hand during low tide.
2. A marine bivalve mollusk with a long, slightly curved shell resembling a jackknife, that burries itself in sand or mud and is often found in shallow waters along the coast. NOUN
   • While walking along the beach, we found several jackknife clams burried in the wet sand.
3. Marine clam having a long narrow curved thin shell. NOUN
   • The jackknife clam quickly disappeared into the sand when we approached.
4. Type of bivalve mollusk characterized by its long, straight, razor-like shell, residing beneath the sandy surface of intertidal mudflats or near the high tide line in temperate seas around the world. NOUN
   • The long, slender shells of jackknife clams are often found washed up on the beach.

Synonyms:

• ensis minor clam
• razor clam