1. counter; counting device
2. (service) counter (at a bank, store, etc.)
カウンター越しに受け取って、店を出る。I receive it over the counter and leave the store.
3. counter (at a bar, cafe, etc.); bar
彼女はカウンターの椅子に一人で座って本を読んでいた。She was sitting alone on a counter stool, reading a book.
4. counter-attack (in soccer)
5. counter; counterpunch
6. automatically responding with an upload slot to someone who allows you to download (e.g. in P2P systems)