What term is used to describe animals with backbones?

The term used to describe animals with backbones is "vertebrates." This classification includes a wide range of animals, such as mammals, birds, reptiles, amphibians, and fish. Vertebrates are distinguished from invertebrates, which are animals that lack a backbone. The presence of a backbone, or vertebral column, allows for greater structural stability and mobility in vertebrates compared to their invertebrate counterparts.

While "chordates" refers to a broader group that includes vertebrates and some other animals that possess a notochord at some stage in their development, it is not exclusively defined by the presence of a backbone. Therefore, while all vertebrates are chordates, the specific term that directly describes animals with backbones is vertebrates.

The term "endotherms" pertains to organisms that regulate their body temperature internally, such as birds and mammals, and is not related to the presence or absence of a backbone. Similarly, "invertebrates" describe animals without backbones, which would not apply to the question at hand.