Definition of plumb inchiefly British
- I plumbed in the washing machine.
: a lead weight attached to a line and used to indicate a vertical direction
: straight down or up : vertically
: to a complete degree : absolutely
: in a direct manner : exactly
: to weight with lead
: to measure the depth of with a plumb
: to examine minutely and critically
: exactly vertical or true
: thorough, complete
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