When needed
When necessary and when needed are semantically related. In some cases you can use "When necessary" instead an adverb phrase "When needed".
When necessary
When needed and when necessary are semantically related. You can use "When needed" instead an adverb phrase "When necessary".
Mutual synonyms
Cite this Source
When necessary and When needed. (2016). Retrieved 2026, August 01, from https://thesaurus.plus/related/when_needed/when_necessary
When needed & When necessary. N.p., 2016. Web. 01 Aug. 2026. <https://thesaurus.plus/related/when_needed/when_necessary>.
When necessary or When needed. 2016. Accessed August 01, 2026. https://thesaurus.plus/related/when_needed/when_necessary.
Google Ngram Viewer shows how "when needed" and "when necessary" have occurred on timeline