Definitions:
the lowest point or part of something

a person's buttocks

stamina or strength of character

a man who takes the passive role in anal intercourse with another man.

in the lowest position

denoting a flavour (variety) of unstable quark having an electric charge of -1/3. bottom quarks have similar properties to down quarks and strange quarks, but are distinguished from them by having a larger mass.

(of a situation) reach the lowest point before stabilizing or improving

(of a ship) reach or touch the ground under the sea