constant - noun

a quantity that does not vary

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

constant - adjective

• steadfast in purpose or devotion or affection
• unvarying in nature
• uninterrupted in time and indefinitely long continuing

constant - thesaurus

ceaseless   changeless   incessant   invariable   invariant   perpetual   unceasing   unremitting   unvarying