Plastic is a synthetic material that can be molded when soft and formed into a solid shape. Many toys are made out of plastic, like Barbie dolls and Lego blocks.
Plastic appears in many different forms, from beach balls to lawn chairs, grocery bags and much more. Credit cards, which are made of plastic, are called plastic, meaning payment that's not cash. You can also use plastic as an adjective to describe things that can be molded, like clay that's plastic in your hands, or to describe something that's artificial. For example, if a person is called plastic, he or she is probably fake or insincere.