constant (adj.)

late 14c., "steadfast, resolute," from Old French constant (14c.) or directly from Latin constantem (nominative constans) "standing firm, stable, steadfast, faithful," present participle of constare, from com "with, together" (see com-) + stare "to stand," from PIE root *sta- "to stand, make or be firm." Of actions and conditions from 1650s. Related: Constantly.

constant (n.)

1832 in mathematics and physics, from constant (adj.).