Meaning

1 senses
  1. (idiomatic, not comparable)Sound asleep, usually from a healthy exhaustion.

    The kids are sacked out in the back seat.

Origin

Outgrowth of the earlier idiom, to hit the sack (“to lie down to sleep”), with possible in

Outgrowth of the earlier idiom, to hit the sack (“to lie down to sleep”), with possible influences from other senses of to sack (“to tackle, to pillage”), and to sock (“to hit, to slam”), providing an implication that sleep has been thrust upon a person.

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sacked out — meaning, examples, forms, synonyms | Krumeto