Real Dictionary

ultimate
You use ultimate to describe the best possible example of a particular thing.
You use ultimate to describe the final result or aim of a long series of events.
You use ultimate to describe the most extreme and unpleasant example of a particular thing.
You use ultimate to describe the most important or powerful thing of a particular kind.
You use ultimate to describe the original source or cause of something.

ultimate in American English
beyond which it is impossible to go; farthest; most remote or distant
something ultimate; final point or result, fundamental principle, etc.
adjective: last; furthest or farthest; ending a process or series
noun: the final point; final result

ultimate in British English
adjective: conclusive in a series or process; last; final
noun: the most significant, highest, furthest, or greatest thing