I. ˈplə-mət noun
Etymology: Middle English plomet, from Anglo-French plumet, plomet, from plum lead, lead weight — more at plumb
Date: 14th century
: plumb ; also : plumb line
II. intransitive verb
Date: 1937
1. : to fall perpendicularly
birds plummet ed down
2. : to drop sharply and abruptly
prices plummet ed