plumbs

1. measure (the depth of a body of water).

   I plumbed the depth and found the bottom of the shelf to be seven metres down

2. test (an upright surface) to determine the vertical.

   they are valuable aids in plumbing the frames and keeping the side of the ship fair

plural noun

a ball of lead or other heavy object attached to the end of a line for finding the depth of water or determining the vertical on an upright surface.

Middle English (originally in the sense ‘sounding lead’): via Old French from Latin plumbum ‘lead’.

1. install an appliance such as a bath, toilet, or washing machine and connect to water and drainage pipes.

   he had plumbed in a second-hand washing machine

late 19th century (in the sense ‘work as a plumber’): back-formation from plumber.