Snobbish means acting like you're better than other people because of superficial things like money, status, or taste. A snobbish person looks down on others who don't have the same advantages, interests, or background as they do.

Someone acting snobbish might refuse to be friends with classmates whose families have less money, or mock another student for not knowing about some fancy restaurant. A snobbish attitude shows up when people treat others as inferior for arbitrary reasons: the wrong clothes, the wrong hobbies, the wrong neighborhood.

A snob (the noun form) is someone who regularly acts this way.

When someone brags that their vacation was “too sophisticated” for most people to understand, or rolls their eyes at a classmate's enthusiasm for something they consider beneath them, that's snobbishness (the noun form describing this attitude).

The opposite of snobbish is being down-to-earth or humble: treating everyone with equal respect regardless of their background or circumstances. You can appreciate quality or have refined tastes without being snobbish about it. The difference is whether you use those things to connect with people or to separate yourself from them.