Ultimate = (1) being or happening at the end of a process ; final ;last.
- Their ultimate aim was to conquer the topmost position in the business.
- The boss will make the ultimate decision who to employ.
- (2) the best available of its kind.
- This restaurant is described as ” the ultimate in luxury”.
- He is believed to be the ultimate painter of this century.
Penultimate = second from the last ; last but one in a series of things.
- The penultimate chapter of the book.
- It’s the penultimate episode of the serial.
Antepenultimate = third from the last.
- The antepenultimate item on the agenda.
- X is the antepenultimate letter of the English alphabet.