Whether you're talking about your glee club or a powerful nation, the word democracy describes government based on participation of the people, either directly or through elected representatives.
Democracy traces back to the Greek words demos, meaning "people," and kratia, meaning "power." "People power" remains central to democracy, whether you're describing a country or a much smaller organization. If your glee club is run as a democracy, then everybody gets to vote on questions like what you're going to sing and what kind of outfits you’re going to wear. Because democracy assumes some idea of equality, it's often used to mean a just society, one in which everyone is treated equally.