Liquefaction

Definition:

(n.) The state of being liquid.
(n.) 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.
(n.) The act or operation of making or becoming liquid; especially, the conversion of a solid into a liquid by the sole agency of heat.

Compare liquefaction with other words:

condensation vs. liquefaction