Definition of prime
(Entry 1 of 3)
1a
often capitalized
: the second of the canonical hours
b
: the first hour of the day usually considered either as 6 a.m. or the hour of sunrise
3
: the most active, thriving, or satisfying stage or period
in the prime of his life
4
: the chief or best individual or part : pick
prime of the flock, and choicest of the stall— Alexander Pope
5
: prime number
6a
: the first note or tone of a musical scale : tonic
b
: the interval between two notes on the same staff degree
7
: the symbol ′ used to distinguish arbitrary characters (such as a and a′), to indicate a specific unit (such as feet or minutes of time or angular measure), or to indicate the derivative of a function (such as p′ or f′(x)) — compare double prime
8
: prime rate
prime
adjectiveDefinition of prime (Entry 2 of 3)
1
: first in time : original
2a
: of, relating to, or being a prime number — compare relatively prime
b
: having no polynomial factors other than itself and no monomial factors other than 1
a prime polynomial
c
: expressed as a product of prime factors (such as prime numbers and prime polynomials)
a prime factorization
3a
: first in rank, authority, or significance : principal
a prime example
b
: having the highest quality or value
prime farmland
c
: of the highest grade regularly marketed
—used of meat and especially beef
4
: not deriving from something else : primary
prime
verb
primed; priming
Definition of prime (Entry 3 of 3)
3
: to apply the first color, coating, or preparation to
prime a wall
4a
: to put into working order by filling or charging with something
prime a pump with water
b
: to supply with an essential prerequisite (such as a hormone, nucleic acid, or antigen) for chemical or biological activity
primed female mice with estrogen
5
: to instruct beforehand : coach
primed the witness
6
: stimulate
: to become prime
prime the pump
: to take steps to encourage the growth or functioning of something
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
February 2021 Words of the Day Quiz
-
- Which is a synonym of perdure?

Test your vocabulary with our 10-question quiz!
TAKE THE QUIZ
Anagram puzzles meet word search.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridged
Words at Play
Ask the Editors
Word Games
-
February 2021 Words of the Day Quiz Take the quiz
-
More Confusing Words—Quiz
How many of these commonly confused words do you ...
Take the quiz -
How Strong Is Your Vocabulary?
Test your vocabulary with our 10-question quiz!
Take the quiz -
SCRABBLE® Sprint
SCRABBLE® fans, sharpen your skills!
Play the game
Share prime
Time Traveler for prime
The first known use of prime was before the 12th century
See more words from the same century