Toward the rear or back of a ship or aircraft.
From Old English 'æftan' meaning 'behind' or 'after.' It's a nautical term that's been used for centuries in maritime vocabulary.
Aft is one of those words that separates sailors from landlubbers—nobody uses 'aft' in everyday English, but sailors use it constantly because on a ship or plane, you need precise directional language for safety.
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