IPA: /ˈɪəˌwɪtnəs/
KK: /ˈɪrˌwɪtnəs/
A person who has heard something and can provide information about it.
The earwitness testified in court about what they heard during the incident.
Earwitness → It is formed from "ear" (from Old English "eare", meaning the organ of hearing) and "witness" (from Old English "witan", meaning to know or to see). The word "earwitness" refers to someone who hears an event and can testify about it, thus combining the act of hearing with the role of a witness.
Think of someone who 'hears' ('ear') something and can 'testify' ('witness') about it — that's what an earwitness does.