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."