1 : to dissolve or melt away
2 : to become soft or liquid with age or maturity — used of some fungal structures (as the gills of a mushroom)
"Deliquesce" derives from the prefix "de-" ("completely, away") and a form of the Latin verb "liquēre," meaning "to be fluid." Things that deliquesce, it could be said, turn to mush in more ways than one. In scientific contexts, a substance that deliquesces absorbs moisture from the atmosphere until it dissolves in the absorbed water and forms a solution. When plants and fungi deliquesce, they lose rigidity as they age. When "deliquesce" is used in non-scientific contexts, it is often in a figurative or humorous way to suggest the act of "melting away" under exhaustion, heat, or idleness, as in "teenagers deliquescing in 90-degree temperatures."