an introductory textbook
"The students used the new math primer to learn basic addition and subtraction before moving on to more advanced topics."
the first or preliminary coat of paint or size applied to a surface
"Before painting the new wall, I need to apply a primer to ensure the color looks even and lasts longer."
A prayer or devotional book intended for laity, initially an abridgment of the breviary and manual including the hours of the Virgin Mary, 15 gradual and 7 penitential psalms, the litany, the placebo and dirige forming the office of the dead, and the commendations.
"The miner carefully attached a detonator primer to the charges before signaling everyone to clear the tunnel."
Any substance or device, such as priming wire or blasting cap, used to ignite gunpowder or other explosive.
In plain English: A primer is a basic introduction to a subject that helps you learn before tackling more advanced material.
"Before painting the wall, she applied a coat of primer to help the color stick better."
Usage: A primer is a devotional book for laypeople that originally contained abridged prayers and the hours of the Virgin Mary. In modern contexts, it also refers to an igniter device used to start explosives like gunpowder or blasting caps.
First in time, initial, early.
"The primer course introduced the basic concepts before moving on to advanced topics."
In plain English: A primer adjective is used to describe something that comes first, like an introduction before you learn more about a topic.
"The primer coat made the red paint look much brighter on the wall."
The word "primer" comes from Medieval Latin terms meaning a prayer book, which was used in England during the Middle Ages. Because these religious texts were often employed to teach children how to read, the term eventually shifted its meaning to refer specifically to schoolbooks for beginners.