Does Plum mean straight?
Keeping this in consideration, what does Plum mean in slang?
Yes you hear it a lot in London, or at least the north of London, to mean 'someone foolish' or 'an idiot'. The term plum is widely used to describe someone who is an idiot, or to use other colloquial terms knob or bell end.
Also, is it plum or plumb? Plum is only ever a noun (though it's a noun with adjectival tendencies). Plumb as a noun refers to a lead weight that's attached to a line and used especially to indicate a vertical direction. It's often used in the phrases "out of plumb" and "off plumb" to mean "out of vertical or true," or "not precisely vertical."
Likewise, people ask, what does it mean to plumb something?
When something is plumb, it means it's straight up and down. If a post installed in flat ground is leaning in any direction, it's out of plumb. If it's at a 90-degree angle to the ground on all sides, it's plumb.
Where does the phrase Plum Crazy come from?
A woman in Hemet, California, wonders about plumb crazy, as in totally, completely crazy. The plumb in this case has to do with a plumb line, a line often weighted with lead to determine verticality. This plumb derives from Latin word for the element lead, plumbum, which is abbreviated on the periodic table as Pb.