"pertaining to or situated near a tail," 1660s, from Latin cauda "tail of an animal," which is of unknown origin, + -al (1).
Entries linking to caudal
-al 1
suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).