[Dead Dog]

KIAS, is Knots Indicated Air Speed.

Indicated means that it is what the airplane actually "feels", and is what the airspeed indicator actually reads. This is important because as you go higher your indicated airspeed decreases for any "True" airspeed (KTAS). This is due to decreasing air density with altitude.

Airspeed indicators really measure dynamic pressure (1/2 density XV^2), which is what determines the aerodynamic forces on the machine, and hence it's operating limitations.

[Dead Dog]

I should say; airspeed indicators measure dynamic pressure (hold you hand out the window of a moving car, that pretty much is dynamic pressure) and are calibrated to read the corresponding airspeed assuming standard Sea Level density.