also: ねごみ
being asleep in bed; being sick in bed
Refers to the state of being in bed, either sleeping or ill. Often used in phrases like 寝込みを襲う (to attack someone while they are asleep) or 寝込みに (while someone is in bed).
The burglar attacked while the victim was asleep and stole the money.
He got angry because he was called while he was in bed.
Standard kanji spelling for the reading ねこみ.
Alternate reading ねごみ is less common; ねこみ is the usual pronunciation.
Noun form of the verb 寝込む (ねこむ), from 寝 (ね, 'sleep') + 込む (こむ, 'to go into, to be deep in').