My sell side died… What should I put on my CV?

I had a terminated deal and it was actually the best experience I had, so I put it at the top of my resume bullet point.

That said, I think "terminated" is fine and I don't think it raises any question on your ability to execute. I do think, if anything, it will get more attention during interview and you should be able to talk about the transaction process and the rationale for it falling apart. I think having your own thoughts on the transaction (whether it would've been a good deal for the seller/buyer) would also be a useful discussion point.