say it: KLAM-shel
clamshell is a noun meaning "the shell of a clam". It carries 2 recorded senses.
the shell of a clam
a dredging bucket with hinges like the shell of a clam
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for clamshell come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.