a small mass of lead or other heavy material, as that suspended by a line and used to measure the depth of water or to ascertain a vertical line. Compare plumb line .

true according to a plumb line; perpendicular.

Informal . downright or absolute.

in a perpendicular or vertical direction.

exactly, precisely, or directly.

Informal . completely or absolutely

She was plumb mad. You're plumb right.

to test or adjust by a plumb line.

to make vertical.

Shipbuilding . horn ( def. 31 ) .

to sound with or as with a plumb line.

to measure (depth) by sounding.

to examine closely in order to discover or understand

to plumb someone's thoughts.

to seal with lead.

to weight with lead.

to provide (a house, building, apartment, etc.) with plumbing.

to work as a plumber. ?

out of or off plumb

not corresponding to the perpendicular; out of true.

adjective

flat , horizontal , level

verb

leave alone

adjective

erect , perpendicular , sheer , straight , straight up , up and down , uprightnotes:a plum is any of numerous varieties of small to medium-sized round or oval smooth-skinned fruit with a single pit , while a plumb is a weight on the end of a line used to determine water depth or used to establish a true vertical , upright

verb

delve , explore , fathom , gauge , get to the bottom of , measure , penetrate , search , sound , take soundings , unravelnotes:a plum is any of numerous varieties of small to medium-sized round or oval smooth-skinned fruit with a single pit , while a plumb is a weight on the end of a line used to determine water depth or used to establish a true vertical , plume , probe , solve