There is. Вторник, четверг, and пятница all refer to the second (второй), fourth (четвёртый), and fifth (пятый) days of the week. The word среда (Wednesday) refers to the middle [of the week]. Понедельник (Monday) means "day after do nothing," meaning the day after Sunday, the day of rest. By the way, Sunday, in other Slavic languages, is often some form of "nedele," implying "do nothing," or it may refer to the week in general. The current Russian word for Sunday, воскресенье, is almost identical to the word for "resurrection" (воскресение). Lastly, Saturday (суббота) is simply the Sabbath.