What does prime mean?
Prime is most commonly used as an adjective meaning chief, most important, or of the highest quality. A prime example is a particularly clear illustration of something, and a prime concern is the issue that matters most. The word can also describe something at its best or most advantageous, as in “a prime opportunity,” or refer to an early stage of life or development. In mathematics, a prime is a number greater than one that has no positive divisors except one and itself. As a noun, “prime” can mean a prime number, the period of greatest activity or quality in someone’s life, or the time when a program or performance has the largest audience. As a verb, it means to prepare something for use or fill a device with fuel, charge, or another substance.
Chief or most important; of first rank or quality; or occurring at the most suitable time.
"The museum selected an especially prime example of the artist’s early work."
Common in formal and informal English. “Prime” often suggests priority, excellence, or suitability.
A prime number; a person or thing in the best condition; or a period of greatest activity or quality.
"The mathematician announced that the new number was a prime."
The mathematical sense is standard in formal mathematical English. The expression “in the prime of life” is idiomatic and often describes someone at the height of their physical or professional powers.
To prepare a person or mechanism for action, or to fill or charge a device with fuel, electricity, or another substance.
"The technician primed the pump before starting it."
The verb is used with equipment, engines, weapons, pumps, and people being prepared for a demanding task.
The same word that describes the most important person in a room can also mean a number divisible only by one and itself.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does prime come from?
The adjective and noun ultimately come from Latin primus, meaning “first” or “earliest,” a form related to the root word for “one.” The English word entered Middle English in senses involving firstness, priority, and numerical primality. Its mathematical sense developed from the idea of a first or fundamental number, later called a prime number.
Related word forms
How prime is actually used
When used to mean the best or most suitable option, prime is often followed by “for”: “a prime candidate.” In the sense of earliest or first stage, it is commonly used before words such as “concern,” “motive,” and “example.”
Easily confused with prime
As an adjective, prime means chief or most important, while as a noun it can mean a prime number or a person or thing in the best condition; as a verb, it means to prepare or fill.