When necessary
When needed and when necessary are semantically related. In some cases you can use "When needed" instead an adverb phrase "When necessary".
When needed
When necessary and when needed are semantically related. You can use "When necessary" instead an adverb phrase "When needed".
Mutual synonyms
Cite this Source
When needed and When necessary. (2017). Retrieved 2026, August 01, from https://thesaurus.plus/related/when_necessary/when_needed
When necessary & When needed. N.p., 2017. Web. 01 Aug. 2026. <https://thesaurus.plus/related/when_necessary/when_needed>.
When needed or When necessary. 2017. Accessed August 01, 2026. https://thesaurus.plus/related/when_necessary/when_needed.
Google Ngram Viewer shows how "when necessary" and "when needed" have occurred on timeline