To thaw out something that is frozen, or to remove frost from something like a freezer or windshield.
Combining the prefix 'de-' (to reverse) with 'frost' (ice crystals/frozen state). This modern word became common in the 1950s with home appliance terminology.
Defrost is a perfect example of how English creates new words just by adding prefixes—we didn't need it until refrigerators became household items! It's a cousin to 'defuse,' 'debug,' and 'decode'—all showing how 'de-' became the go-to prefix for 'undoing' something.
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