Definition of "Tuck" :

noun: a straight sword with a narrow blade and two edges

noun: a narrow flattened pleat or fold that is stitched in place

noun: (sports) a bodily position adopted in some sports (such as diving or skiing) in which the knees are bent and the thighs are drawn close to the chest

noun: eatables (especially sweets)

verb: draw together into folds or puckers

verb: fit snugly into

"Tuck your shirttail in."

verb: make a tuck or several folds in

"Tuck the fabric."