What is the meaning of Antifreeze?

A substance, such as glycol, used to lower the freezing point of water;

Automotive antifreeze, a solution of ethylene glycol, used as an additive to water or replacement for water, in the radiators of motorcars.

Deicer, a heated glycol solution used to remove ice from the aerodynamic surfaces of airplanes, and prevent icing while on the tarmac.

Source: wiktionary.org