When something is the opposite of another thing, it's as different from it as possible. North is the opposite of south. Hot is the opposite of cold. A full glass is the opposite of an empty one.

The word helps us understand things by contrast. If you know what brave means, thinking about its opposite (cowardly) makes the meaning even clearer. If someone describes their new teacher as the opposite of their old one, you immediately understand they're very different: maybe strict instead of relaxed, or serious instead of funny.

In math, opposite numbers sit on different sides of zero but the same distance away. Five and negative five are opposites. When you move in the opposite direction, you turn around completely: if you're walking east and then head in the opposite direction, you're now walking west.

Sometimes people say “opposites attract” when describing friends or couples who are very different from each other. One might be talkative while the other is quiet, or one loves sports while the other prefers reading. These differences can complement each other.