The prefix 'penta' is derived from the Greek word for five, and is used to describe something that has five parts or components. It is commonly used in scientific terms, such as pentagon (a five-sided shape) and pentagram (a five-pointed star). It can also be used to describe a group of five people or things, such as a pentad or pentarchy. In general, the prefix 'penta' is used to refer to anything related to the number five.