I've tried to design this grid to be extra hard. I don't know how achievable it is, but I'm sure it'll be somewhat educational at the very least.

It's actually not that bad, but relies on vocabulary more than usual. Snapdragon was a way in, and each of the other groups had a couple terms I knew so I could trial-and-error my way to eventual success. Ended up running out of lives for 7/10, but my next guess would have taken me to 10/10.

2 quibbles: hydrophobia and quinsy are more symptom than disease, and the "quisling" group should accept "eponymous" as a link. Otherwise, enjoyable!

Hydrophobia is simultaneously a symptom and an older name '2. A term once commonly used for rabies because in the later stages of that disease, the animal (or person) has difficulty swallowing and so fears a drink of water.'

Quinsy is straight up an alternate name 'Quinsy, also known as a peritonsillar abscess, is a rare and potentially serious complication of tonsillitis.'

I should've accepted eponymous true. Didn't think of it. I do partly think the emphasis is on the answerer to give as many synonymous or tautological terms to give themself the chance to win the round. But I take the critique.