I mean ‘g’. 1g is 9.81m/s^2. c is a speed, not an acceleration. g is acceleration.

Not coincidentally, it’s the acceleration you experience from Earth’s gravity, but it doesn’t have to come from gravity. Astronauts routinely experience 3gs during takeoff from their rocket boosters.

If you were in a rocket that accelerated at a constant 1g it would feel like Earth’s gravity, even in space.