Having no door or lacking a door; open without a barrier at the entrance.
From Old English 'duru' (door) + '-less' suffix meaning without. The '-less' suffix comes from Old English 'lēas' meaning destitute or free from, ultimately from Proto-Germanic roots meaning empty or lacking.
Medieval castles often had doorless openings called 'postern gates' that allowed secret movement between sections—the absence of a door was actually a strategic military feature! This shows how what seems like a simple architectural absence can be a deliberate design choice.
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