constant constant /ˈkɑːnstənt/

adjective

1. () Unvarying in nature  ( changeless , invariant , unvarying , constant )
   unvarying in nature
    Maintained a constant temperature
   maintained a constant temperature
    Principles of unvarying validity
   principles of unvarying validity
   
2. () Steadfast in purpose, devotion or affection  ( constant )
   steadfast in purpose, devotion or affection
    A man constant in adherence to his ideals
   a man constant in adherence to his ideals
    A constant lover
   a constant lover
    Constant as the northern star
   constant as the northern star
   
3. Uninterrupted in time and indefinitely long continuing  ( constant , incessant , never-ending , ceaseless , perpetual , unceasing , unremitting )
   uninterrupted in time and indefinitely long continuing
    The ceaseless thunder of surf
   the ceaseless thunder of surf
    In constant pain
   in constant pain
    Night and day we live with the incessant noise of the city
   night and day we live with the incessant noise of the city
    The never-ending search for happiness
   the never-ending search for happiness
    The perpetual struggle to maintain standards in a democracy
   the perpetual struggle to maintain standards in a democracy
    Man's unceasing warfare with drought and isolation
   man's unceasing warfare with drought and isolation
    Unremitting demands of hunger
   unremitting demands of hunger
   

noun

1. () A quantity that does not vary  ( constant quantity , invariable , constant )
   a quantity that does not vary
   
2. A number representing a quantity assumed to have a fixed value in a specified mathematical context  ( constant )
   a number representing a quantity assumed to have a fixed value in a specified mathematical context
    The velocity of light is a constant
   the velocity of light is a constant