Complex sentence: A clade (from Ancient Greek, "klados", "branch") is a group consisting of a species (extinct or extant) and all its descendants, a single "branch" on the "tree of life".
Split into simpler sentences: A clade (from Ancient Greek, "klados", "branch") is a group consisting of a species (extinct or extant) and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life".