If something is silent, it is completely quiet. After your noisy houseguests leave, you'll probably enjoy being all alone in your silent house.
Sometimes a silent reading period in a third grade class truly is silent — and other times, the sound of soft giggling can be heard. People are silent when they don't speak, and a silent film has no soundtrack. You might exchange a silent message with your best friend without using words, just by raising your eyebrows or shrugging your shoulders. The Latin root of silent is silere, "be quiet or still."