dear rabia
imagine you have a six membered ring, a cyclohexane, or if its easier, six poles attached at each end in a ring. A puckered ring is when the ring bends, and two opposite ends bend upwards, forming a kind of boat structure. rings can also be in a chair type of shape, with one end pointing upward, and the opposite end facing downwards, making a kind of lounge chair shape.
simply – when the ring goes up and down , and its not flat , its called as puckered ring .
HOPE IT CLEARS
REGARDS