Plain English Meaning
Full Definition
To remove ice that has already formed on an aircraft surface, typically by mechanical action, heat, or chemical fluids. Deicing systems and procedures are reactive — they act after ice has accumulated, in contrast to anti-icing, which prevents ice from forming in the first place.
Context Anchor
Used in cold-weather preflight, ground handling, and systems discussions when ice has formed on the airplane.
Derivation
The prefix 'de-' comes from Latin, meaning 'remove' or 'reverse.' So 'deice' literally means 'remove ice' — which is exactly what it does.