Literally meaning to set the tone of a gong with a single hammer blow; used to describe making a final decision or a closing statement that settles a matter once and for all.

A percussion instrument used primarily in orchestras, consisting of a copper bowl covered with a skin that can be tightened or loosened to adjust the pitch; kettledrum.

Literally "to fix the tone with a single hammer blow"; to have the final word or settle a matter once and for all