Don't you hate when you get Tinnitus?
I've experienced Tinnitus a few times, luckily not for long, and I think that that is the only reason I even know what Tinnitus is. I have no idea about native English speakers but I don't think many non-native English speakers have any idea what Tinnitus is.
So today, a Japanese word and an English word for the same price :P
Literally: ear + ringing
That's right. Tinnitus is that annoying ringing sound you sometimes start to hear in your ear out of nowhere. I don't know if Japanese has a more medical term for it, but it doesn't stop me from getting amused by thinking of the doctor talking to the nurse and saying "Yes, I examined the patient and my educated diagnosis is that he suffers from ear-ringing-ness." :P