plumb
🇺🇸
/plʌm/
🇬🇧
/plʌm/
to try to understand something that is not clear or is difficult to understand
She spent her life trying to understand the mysteries of the human mind, which is like plumbing the depths of a deep ocean.
exactly or directly
He was standing right in the middle of the road, like a flagpole, plumb straight.
completely or totally
He's not just a little bit crazy, he's plumb crazy.