When you dip something, you plunge it quickly into a liquid or soft substance. You might dip your toe into a swimming pool to check the water temperature.
When you finger paint, you dip a fingertip into a puddle of paint, and when you eat a snack you might dip tortilla chips into salsa. You can also say that a boat bobbing on the ocean dips, or that a bird dropping lower in the sky dips down. A dip can be a quick swim, a delicious sauce meant for dunking other foods in, or a downward slope. The Old English root, dyppan, means "immerse" or "baptize."