Definition of "Constant" :

noun: a quantity that does not vary

noun: a number representing a quantity assumed to have a fixed value in a specified mathematical context

"The velocity of light is a constant."

adjective: steadfast in purpose or devotion or affection

"A man constant in adherence to his ideals."

adjective: uninterrupted in time and indefinitely long continuing

"In constant pain."

adjective: unvarying in nature

"Maintained a constant temperature."