external auditory canal vs acoustic meatus

external auditory canal and acoustic meatus both are nouns.

Word	Noun	Adjective	Verb	Adverb
external auditory canal	Yes	No	No	No
acoustic meatus	Yes	No	No	No

As nouns, external auditory canal and acoustic meatus are synonyms defined as:

external auditory canal and acoustic meatus: either of the passages in the outer ear from the auricle to the tympanic membrane

Other synonyms of external auditory canal include auditory canal, auditory meatus, ear canal.

external auditory canal (noun)	acoustic meatus (noun)
either of the passages in the outer ear from the auricle to the tympanic membrane	either of the passages in the outer ear from the auricle to the tympanic membrane