— plumbable , adj. — plumbless , adj. — plumbness , n.
/plum/ , n.
1. 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. Cf. plumb line .
2. out of or off plumb , not corresponding to the perpendicular; out of true.
adj.
3. true according to a plumb line; perpendicular.
4. Informal. downright or absolute.
adv.
5. in a perpendicular or vertical direction.
6. exactly, precisely, or directly.
7. Informal. completely or absolutely: She was plumb mad. You're plumb right.
v.t.
8. to test or adjust by a plumb line.
9. to make vertical.
10. Shipbuilding. horn (def. 35).
11. to sound with or as with a plumb line.
12. to measure (depth) by sounding.
13. to examine closely in order to discover or understand: to plumb someone's thoughts.
14. to seal with lead.
15. to weight with lead.
16. to provide (a house, building, apartment, etc.) with plumbing.
v.i.
17. to work as a plumber.
Also, plum (for defs. 3-7).
[ 1250-1300; ME plumbe, prob. plombe plumba, for L plumbum lead ]
Syn. 3. vertical, straight, square.