Other forms: tucked; tucking; tucks
To tuck is to fold, gather, or insert, like the way you tuck your sheets under your mattress when you make the bed in the morning or the way you tuck your lucky stuffed unicorn into your backpack on the day of a big test.
You can tuck your shirt into your waistband, and tuck your jeans into your cowboy boots. You can also tuck a child into bed or tuck your book under your arm to carry it. The verb tuck can also be used informally to mean "eat with gusto," like when you tuck into a giant bowl of spaghetti.