tampion

tam·pi·on  (tmp-n) also tom·pi·on (tm-)

n.

A plug or cover for the muzzle of a cannon or gun to keep out dust and moisture.

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[Middle English, from Old French tampon, variant of tapon, rag for stopping a hole, of Germanic origin.]

Thesaurus

Noun

1.

tampion - plug for the muzzle of a gun to keep out dust and moisture tompion plug, stopple, stopper - blockage consisting of an object designed to fill a hole tightly