The word “Ontlasting” itself has nine letters, not five.
Assuming you’re looking for a five-letter word related to “outlasting” (which could be derived from “ontlasting”), here are some options:
- Outdo (surpass someone in achievement)
- Outgo (exceed something in amount)
- Outlive (live longer than someone or something)
- Outlast (last longer than someone or something)
If you have any other clues or context for the puzzle, I might be able to provide a more specific answer.