IPA: /ˈdɛfən/
KK: /ˈdɛfən/
To make someone unable to hear, either temporarily or permanently.
The loud explosion could deafen anyone nearby.
Past: deafened
Past Participle: deafened
To cause someone to lose the ability to hear, often temporarily, usually due to a loud noise.
The explosion was so loud that it could deafen anyone nearby.
Past: deafened
Past Participle: deafened
Deafen is formed from "de-" (meaning down or away) and "fenn" (from Old English "fēon", meaning to make sound). The word describes the act of making someone unable to hear by taking away their ability to hear sounds.
Think of 'taking away' ('de-') the ability to 'hear' ('fenn') — that's why deafen means to make someone unable to hear.