knife-handle vs jackknife clam

knife-handle and jackknife clam both are nouns.

Word	Noun	Adjective	Verb	Adverb
knife-handle	Yes	No	No	No
jackknife clam	Yes	No	No	No

As nouns, knife-handle and jackknife clam are synonyms defined as:

knife-handle and jackknife clam: marine clam having a long narrow curved thin shell

Other synonyms of knife-handle include razor clam.

knife-handle (noun)	jackknife clam (noun)
marine clam having a long narrow curved thin shell	marine clam having a long narrow curved thin shell