- To tuck in is to pull the bed covers up and over someone as part of a bedtime routine.
An example of tuck in is when a parent pulls a child's covers up to his chin and then kisses him goodnight.
tuck-in definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
Brit., Informal a meal, esp. a hearty one
tuck-in - Phrases/Idioms
Thrust in the edge of or end of something, such as bed linens or a shirt; also, make a child secure in bed by folding in the bedclothes. For example, Tuck in your shirt; it looks awful hanging out of your pants, or Mother went upstairs to tuck in the children. [First half of 1600s]