constant
adjective(con-stant)
uninterrupted in time and indefinitely long continuing
Examples:
In constant pain. 
constant
adjective(con-stant)
unvarying in nature
Examples:
Maintained a constant temperature. 
constant
noun(con-stant)
a quantity that does not vary
constant
noun(con-stant)
a number representing a quantity assumed to have a fixed value in a specified mathematical context
Examples:
The velocity of light is a constant. 
constant
adjective(con-stant)
steadfast in purpose or devotion or affection
Examples:
A man constant in adherence to his ideals. 
A constant lover. 
Constant as the northern star.