silenus

noun

si·​le·​nus sī-ˈlē-nəs 

plural sileni sī-ˈlē-ˌnī 

often capitalized

: a minor woodland deity and companion of Dionysus in Greek mythology with a horse's ears and tail

Word History

Etymology

Latin, from Greek silēnos, from Silēnos foster father of Dionysus

First Known Use

1572, in the meaning defined above