Plain and Undefined

Opposite meaning words

Plain adjective - Free from all additions or embellishment.

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Undefined is an antonym for plain.

Nearby Words: plainly, plainness, plaint

Undefined adjective - Not seen or understood clearly.

Usage example: plagued by undefined worries that kept her awake at night

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Plain is an antonym for undefined.

Cite this Source

Undefined and Plain. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/plain/undefined

Plain & Undefined. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/plain/undefined>.

Undefined or Plain. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/plain/undefined.

Google Ngram Viewer shows how "plain" and "undefined" have occurred on timeline