scheduled with more commitments or reservations than can be properly accommodated; having too many bookings.
From 'over-' (exceeding a limit) + 'booked' (from 'book,' originally meaning to record in a book, later to reserve). The compound formed as reservation systems became common.
Airlines intentionally overbook flights because they know some passengers won't show up—it's a statistical gamble that occasionally backfires when everyone shows up and people get bumped.
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