Complimentary
Complimentary adjective - Not costing or charging anything.
Usage example: the airline will continue to give out complimentary soft drinks on all domestic flights
Optional and complimentary are semantically related. In some cases you can use "Optional" instead an adjective "Complimentary".
Nearby Words: compliment, complimented
Optional
Optional adjective - Subject to one's freedom of choice.
Complimentary and optional are semantically related. Sometimes you can use "Complimentary" instead an adjective "Optional".
Nearby Words: option, optionally
Mutual synonyms
Cite this Source
Optional and Complimentary. (2016). Retrieved 2026, July 22, from https://thesaurus.plus/related/complimentary/optional
Complimentary & Optional. N.p., 2016. Web. 22 Jul. 2026. <https://thesaurus.plus/related/complimentary/optional>.
Optional or Complimentary. 2016. Accessed July 22, 2026. https://thesaurus.plus/related/complimentary/optional.
Google Ngram Viewer shows how "complimentary" and "optional" have occurred on timeline