means the process of a solid turning to liquid under heat, or figuratively softening, dissolving, or losing composure.

from From Old English 'meltan,' meaning to dissolve or digest, with roots in a Proto-Germanic word for becoming soft or liquid. It's a distant cousin of words across other Indo-European tongues tied to softening and grinding down — the same deep root that possibly gives us 'mild' and 'mild'-mannered things that yield rather than resist.