con·stant / ˈkänstənt/ • adj. occurring continuously over a period of time: the pain is constant. ∎  remaining the same over a period of time. ∎  (of a person) unchangingly faithful and dependable.• n. a situation or state of affairs that does not change: the condition of struggle remained a constant. ∎  Math. a quantity or parameter that does not change its value whatever the value of the variables, under a given set of conditions. ∎  Physics a number expressing a relation or property that remains the same in all circumstances, or for the same substance under the same conditions.DERIVATIVES: con·stant·ly adv.

constant steadfast XIV; invariable XVI. — (O)F. — L. constāns, -ant-, prp. of constāre stand firm; cf. COST, STAND, and see -ANT.
So constancy XVI. — L. constantia.

constant
1. A quantity or data item whose value does not change.

2. A value that is determined by its denotation, i.e. a literal.

constant In mathematics, a quantity or factor that does not change. It may be universal, such as the ratio of the circumference of a circle to its diameter, or it may be particular, such as a symbol that has a fixed value in an algebraic equation.