I. noun see: plumb Date: 14th century plumb , II. intransitive verb Date: 1937 to fall perpendicularly , to drop sharply and abruptly
PLUMMET
Meaning of PLUMMET in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012