Words similar to optional

Example sentences for: optional

How can you use “optional” in a sentence? Here are some example sentences to help you improve your vocabulary:

Participation was optional and informed consent was obtained for all interactions.
I find Bollard's superior \?\, used to transcribe both the “optional r ” ambiguous.
The bra is a keener pleasure for being optional.
Women's hats are out there, but they're all optional, and the range has shrunk.
Friday night there will be a nondenominational sunset ceremony (optional, but we hope you'll come!)