Opaque is a word that describes a material or color swatch of a solid non-see-through color. Examples of opaque material could be metal or wood. Transparent describes a see-through material that reveals any objects behind it. Examples of transparent material might include glass or water. Plastic comes in both opaque and transparent. Hard plastics are often opaque (but not always), and soft plastics, like plastic bags, are often transparent (but not always). Adobe software products represent a transparent background with a checkerboard pattern. My fourth grade teacher used to say (regarding my level of transparency), "You make a better door than window."