An obsolete spelling of plum.n. A mass of lead attached to a line, used to test the perpendicularity of walls, etc.; a plummet.n. The position of a plumb or plummet when freely suspended; the vertical or perpendicular.True according to a plumb-line; vertical.Of persons, upright in character or conduct; thoroughgoing.In a vertical direction; in a line perpendicular to the plane of the horizon; straight down.Exactly; to a nicety; completely: as, he hit the target plumb in the bull's-eye.Downright; entirely; altogether.To adjust by a plumb-line; set in a vertical position: as, to plumb a wall or a building.To sound with or as with a plummet, as the depth of water.To ascertain the measure, dimensions, capacity, or the like, of; test-To supply, as a building, with lead pipes for water, sewage, etc.In plumbing, to seal an opening by closing it with solder or other soft metal.To coincide in direction with the plumb-line; be vertically above or below.