The Helmholtz free energy, A (the internal energy of a system minus the product of its entropy and absolute temperature)

(of a road or highway) Free to use; not requiring payment of a toll to use. / (US, of a phone call) Without an additional toll, especially for a long-distance charge.

Alternative form of freefall

An area within a port where goods may be temporarily stored without paying duty

Not requiring one's hands to use.

A hands-free phone

Any of various aquatic disciplines in which divers attempt to stay underwater without breathing apparatus for as long as possible.

Of food, drink, medication, chewing gum, etc: not containing sugar (and usually sweetened with a sugar substitute instead).

Free of commitments or obligations / Having no spouse or other partner

Not containing fat.