Liq`ue*fac"tion (-făk"shŭn), n. [L. liquefactio: cf. F. liquéfaction. See Liquefy.] 1. The act or operation of making or becoming liquid; especially, the conversion of a solid into a liquid by the sole agency of heat.

2. The state of being liquid.

3. (Chem. Physics) The act, process, or method, of reducing a gas or vapor to a liquid by means of cold or pressure; as, the liquefaction of oxygen or hydrogen.