The term 'Ultimatum Word' is used to describe words that are used to make a demand or give an ultimatum. The three crossword solutions for this term are ELSE (4 letters), UNLESS (6 letters), and EITHER (6 letters). ELSE is used to indicate that something ELSE must be done if the first option is not chosen. UNLESS is used to indicate that something will not happen UNLESS a certain condition is met. Finally, EITHER is used to indicate that one of two options must be chosen. All three words are used to make demands or ultimatums.