Pronunciation: (pop'it),[key] —n. 1. Also called pop'pet valve".Mach.a rising and falling valve consisting of a disk at the end of a vertically set stem, used in internal-combustion and steam engines.
2. Brit. Dial.a term of endearment for a girl or child.
3. Naut.any of the vertical timbers bracing the bow or stern of a vessel about to be launched.