1.Definition: being at the best stage of development

"Our manhood's prime vigor"

Related Adjective(s):meridian

2.Definition: first in rank or degree

"The prime minister"

Related Adjective(s):premier

3.Definition: of or relating to or being an integer that cannot be factored into other integers

"Prime number"

4.Definition: of superior grade

"Prime beef"

Related Adjective(s):choice, prize, quality, select

5.Definition: used of the first or originating agent

"Prime mover"