If you want the dictionary definition, just double click on any word.

Defrost  is a verb that means to (cause to) become free of ice, or to (cause to) become no longer frozen.

For example: "I had to defrost the fridge before I could defrost the fish from the freezer in it."

Melt is a verb, it means to turn from something solid into something soft or liquid.

For example: "The ice melted in the heat."

!Note - you really don't want to melt the fridge.

Do not melt the fridge