Definition of defrost verb from the Oxford Advanced American Dictionary
defrost
verb
/dɪˈfrɔst/
1[intransitive, transitive]to become or make something warmer, especially food, so that it is no longer frozenIt will take about four hours to defrost.defrost somethingMake sure you defrost the chicken completely before cooking.2[transitive, intransitive]defrost (something)when you defrost a refrigerator or freezer, or when it defrosts, you remove the ice from it compare de-ice, melt, thaw, unfreeze3[transitive]defrost somethingto remove ice from the surface of a car's windowsdefroster