con·stant [kónst?nt] adjective 1. ever present: always present or available constant whining a constant supply of fresh water 2. happening or done repeatedly: occurring or made again and again constant visits to the doctor 3. not changing or varying: remaining the same and not varying with change in other things kept at a constant pressure 4. faithful: faithful and loyal, especially to a husband, wife, or other loved one noun (plural con·stants) 1. something unchanging: an object, quality, or fact that is invariable or ever present This preoccupation has become a constant in our daily lives.