Spanish word oreja comes from Latin marem, Proto-Indo-European *h₂ew-, Proto-Indo-European *h₂ous-, and later Proto-Indo-European *h₂ṓws (Ear.)
marem (Latin)
*h₂ew- (Proto-Indo-European)
*h₂ous- (Proto-Indo-European)
*h₂ṓws (Proto-Indo-European)
Ear.
*auzis (Proto-Italic)
auris (Latin)
(anatomy) ear.
oricla (Vulgar Latin)
oreja (Spanish)