Here are all the possible meanings and translations of the word piano bar. Freebase(0.00 / 0 votes)Rate this definition: A piano bar consists of a piano or electronic keyboard played by a professional musician, located in a cocktail lounge, bar, hotel lobby, office building lobby, restaurant, or on a cruise ship. Usually the pianist receives a small salary plus tips in a jar or basket on or near the piano, especially from patrons requesting a song traditionally written on a beverage napkin.