| noun | a quantity that does not vary |
| noun | a number representing a quantity assumed to have a fixed value in a specified mathematical context “the velocity of light is a constant” |
| adjective | unvarying in nature “maintained a constant temperature” |
| adjective | steadfast in purpose or devotion or affection “a man constant in adherence to his ideals” |
| adjective | uninterrupted in time and indefinitely long continuing “the ceaseless thunder of surf” |
| changelessness | noun | the property of remaining unchanged |
| constancy | noun | the quality of being enduring and free from change or variation |
| invariance | noun | the quality of being resistant to variation |
| ceaselessness | noun | the quality of something that continues without end or interruption |
| incessantness | noun | the quality of something that continues without end or interruption |
| incessancy | noun | the quality of something that continues without end or interruption |
| perpetuity | noun | the property of being perpetual (seemingly ceaseless) |