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1. To sleep the entire night without waking. Our first baby was nearly nine months old before she finally started sleeping through.
2. To remain asleep while something happens. I can't believe you slept through my recital, Dad! I keep sleeping through my alarm in the morning. How on earth did the baby sleep through that racket coming from next door?
sleep through something
to remain sleeping through some event. I didn't hear the storm. I guess I slept through it. Wally slept through the entire opera—even the loud part.
1. Sleep without waking for a period of time, usually the night, as in At three months many babies have learned to sleep through. [Mid-1900s]
2. sleep through something. Fail to pay attention, as in We all slept through the explanation and then had trouble getting the machines started.