prime

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective First or highest in rank or importance; main: synonym: chief.
• adjective Highest in quality; excellent.
• adjective Being the most desired or suitable example of something.
• adjective First or early in time, order, or sequence.
• adjective Mathematics Of, relating to, or being a prime number.
• noun The period of greatest physical and mental robustness.
• noun The period of best performance or peak activity: synonym: bloom.
• noun Mathematics A prime number.
• noun The prime rate.
• noun A mark (′) appended above and to the right of a character, especially.
• noun One used to distinguish different values of the same variable in a mathematical expression.
• noun One used to represent a unit of measurement, such as feet or minutes in latitude and longitude.
• noun The second of the seven canonical hours. No longer in liturgical use.
• noun The time appointed for this service, the first hour of the day or 6 AM.
• noun The first position of thrust and parry in fencing.
• intransitive verb To make ready; prepare.
• intransitive verb To prepare (a gun or mine) for firing by inserting a charge of gunpowder or a primer.
• intransitive verb To prepare for operation, as by pouring water into a pump or gasoline into a carburetor.
• intransitive verb To prepare (a surface) for painting by covering with size, primer, or an undercoat.
• intransitive verb To inform or instruct beforehand; coach.
• intransitive verb To become prepared for future action or operation.
• idiom (prime the pump) To encourage the growth or action of something.

from The Century Dictionary.

• To be as at first; be renewed.
• To insert a primer or priming-powder into the vent of a gun before firing.
• In the steam-engine, to carry over hot water with the steam from the boiler into the cylinder: as, the engine primes. See primage, 2.
• To perform the prime or first operation upon or with; prepare.
• To cover with a ground or first color or coat in painting or plastering.
• To put in a fit state to act or endure; make ready; especially, to instruct or prepare (a person) beforehand in what he is to say or do; “post”: as, to prime a person with a speech; to prime a witness.
• To trim or prune.
• First in order of time; primitive; original: as, the prime cost.
• First in rank, degree, or importance; principal; chief: as, prime minister.
• Of the first excellence, value, or importance; first-rate; capital: as, prime wheat; prime quality; a prime joint of meat.
• Relating to the period or the condition of early manhood and vigor; being in the best or most vigorous time of life. See prime, n., 3.
• Ready; eager; bold.
• Fierce; strong.
• In mathematics, indivisible without a remainder, except by unity; incapable of being separated into simpler factors.
• A machine which receives and modifies force as supplied by some natural source, as a water-wheel or a steam-engine.
• 2 and Chief, principal, best.
• noun The first period; the earliest stage or beginning; specifically, spring.
• noun The first hour or period of the day.
• noun In a more extended sense, from the fact that the lesser canonical hours followed at intervals of three hours, the first quarter of the time between sunrise and sunset, ending half-way between sunrise and midday.
• noun The spring of life; youth; full health, strength, or beauty; hence, the highest or most perfect state or most flourishing condition of anything.
• noun The best part; that which is best in quality; that which is of prime or high quality or grade, as fish, oysters, etc.; often, in the plural, a prime grade or quality.
• noun In fencing: The first of eight parries or guards against thrusts in sword-play, afterward retained in exercise with the foils; the first guard a swordsman surprised by an attack could make, while drawing his weapon from the scabbard near his left thigh.
• noun Hence — Sometimes, the first and simplest thrust (and parry) which can be made after two fencers have crossed foils and are “on guard” with the left sides of their foils touching: used thus for the direct thrust.
• noun In chem., a number employed, in conformity with the doctrine of definite proportions, to express the ratios in which bodies enter into combination.