Real Dictionary

prime
If someone or something is in their prime, they are at the stage in their existence when they are at their strongest, most active, or most successful.
You use prime to describe an example of a particular kind of thing that is absolutely typical.
You use prime to describe something that is most important in a situation.
You use prime to describe something that is of the best possible quality.
verb: If someone primes a bomb or a gun, they prepare it so that it is ready to explode or fire.
verb: If you prime someone to do something, you prepare them to do it, for example by giving them information about it beforehand.

prime in American English
first in time; original; primitive; primary
adjective: of the first importance; demanding the fullest consideration
intransitive verb: to deliver or discharge steam containing an excessive amount of water
noun: the most flourishing stage or state
transitive verb: to prepare or make ready for a particular purpose or operation

prime in Finance
adjective: Prime borrowers are the least risky, most creditworthy borrowers.