What is the X in X-mas?
1847, "pertaining to the ear," from Latin auris "ear" (see ear (n.1)) + -al (1). Meaning "received or perceived by ear" is attested from 1860. Related: Aurally.
aural au·ral1 (ôr'əl)adj. Relating to or perceived by the ear.
aural au·ral2 (ôr'əl)adj. Characterized by or relating to an aura.