Crossword Genius

In negotiations it's the very last word (9)

Ross

I believe the answer is:

ultimatum

I'm a little stuck... Click here to teach me more about this clue!

'last word' is the definition.
(thesaurus)

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for ultimatum that I've seen before include "Final offer" , "Final demand or statement of terms" , "Final warning" , "Final proposition or demand" , "Final (peremptory) demand" .)

I've seen this clue in The Globe and Mail.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.