These words refer to the process by which a solid is transformed into in fluid. Melt is the most general of these, referring to such a transformation of any solid: ice cubes that had already melted; listing the different temperatures at which various metals melt . Used metaphorically, the word indicates any emotional yielding, usually one in which rigidity or indifference gives way to responsiveness or affectionate concern: a story designed to melt the hardest heart; feeling her resistance to him melting away at their first touch. Thaw is a specific instance of melt , stressing the application of heat as the cause of the melting process, and referring mainly to the transformation of ice or snow into water: signs that the snowdrifts had begun to thaw ; wondering when the stream would thaw . But the word has a special use in referring to frozen solids that remain more or less hard even after being subjected to warming: not certain whether the frozen vegetables should be plunged into boiling water or be allowed to thaw out first at room temperature. The word, also, can refer to any warming process: sitting by the fire to thaw out his cold feet. Metaphorically, the word suggests a more gradual yielding to emotional warmth than melt : their ceremonious reserve began to thaw a bit.

Dissolve may function identically with melt: cakes of ice slowly dissolving into puddles. More strictly, the word refers to the specific process by which a solid passes into solution in a solvent: dissolving the tablet in a glass of water; a cleaning agent that dissolves grease stains. By extension, the word is used of any supposed disappearance or eating away of solids: snowbanks that dissolve overnight; erosion that had dissolved acres of topsoil. Metaphorically, the word can suggest a collapse after having yielded to a strong emotion: dissolving into laughter at his discomfiture; dissolving into tears at the news. Liquefy is the most formal of these words and gives a technical or scientific tone. Its usefulness lies in referring generically to any conversion into a liquid state, whether by heat or pressure, and applies both to the conversion of solids and gases: temperatures too low for tungsten to liquefy : using high pressures to liquefy nitrogen. The word is not used to apply metaphorically to emotional states.