Segmented things are divided into separate parts, and segmented animals have bodies made up of distinct sections. An earthworm is one example of a segmented animal.
Although humans clearly aren't segmented the way worms and leeches are, we do have segmented spinal columns, with repeated segments, or vertebrae. You can also use this adjective figuratively to describe things that are broken into separate sections: "The city is divided into distinct, segmented neighborhoods." Segmented comes from the Latin word segmentum, "strips of colored cloth," or "a piece cut off."