Definition
Equipment or procedures used to prevent the formation of ice on aircraft surfaces or components before any ice has accumulated. Anti-ice systems are activated in advance of icing conditions and work by keeping a surface warm or chemically treated so ice cannot bond to it.
Plain English
Anti-ice means stopping ice from forming in the first place. You turn it on before you get into icing conditions, not after ice has already built up.
Context Anchor
Seen in icing discussions, airplane manuals, checklist items, and cockpit switches for protecting wings, windshields, engine openings, and air-sensing parts.
Derivation
The prefix 'anti-' comes from Greek, meaning 'against' or 'preventing.' So anti-ice literally means 'against ice forming' — the prevention side, as opposed to de-ice, which is removal after ice has already appeared.
Why Pilots Care
Ice reduces lift and control effectiveness; anti-ice equipment lets the aircraft continue safe flight in conditions where ice would otherwise accumulate.
Grounding Statement
Anti-ice is preventive protection: it is used when ice is likely, so ice has a harder time forming in the first place.
Intuition Check
Do not read anti-ice as the same thing as removing ice. Anti-ice prevents ice from forming; deicing removes ice that is already there.
Example Sentence 1
Before entering the cloud layer in freezing temperatures, the pilot turned on the engine and pitot anti-ice systems.
Example Sentence 2
Preflight checks confirmed the propeller anti-ice was operational for the flight.