What does liquefaction refer to?

Liquefaction refers to the process of a substance transforming from a solid or gas state into a liquid state. This occurs under specific conditions such as changes in temperature or pressure, which can cause the particles to lose their fixed arrangement in solids or gases and move freely, hence assuming a liquid form. This term is commonly used in various scientific and medical contexts, especially concerning materials and substances that change states. The other options, while related to states of matter, do not accurately describe the process that liquefaction involves.