<p><strong>Adjective</strong></p><ul><li>clear or distinct to the eye or ear: to stand in plain view.</li><li>Synonyms: perspicuous, apparent, unmistakable, intelligible, understandable, lucid</li><li>Antonyms: indistinct</li><li>clear to the mind; evident, manifest, or obvious: to make one's meaning plain.</li><li>Synonyms: transparent, patent, unequivocal, unambiguous, perspicuous, apparent, unmistakable, intelligible, understandable, lucid</li><li>Antonyms: obscure</li><li>conveying the meaning clearly and simply; easily understood: plain talk.</li><li>Synonyms: transparent, patent, unequivocal, unambiguous</li><li>downright; sheer; utter; self-evident: plain folly; plain stupidity.</li><li>free from ambiguity or evasion; candid; outspoken: the plain truth of the matter.</li><li>Synonyms: sincere, open, ingenuous, frank, blunt, direct, straightforward, unreserved</li><li>without special pretensions, superiority, elegance, etc.; ordinary: plain people.</li><li>Synonyms: unpretentious</li><li>not beautiful; physically unattractive or undistinguished: a plain face.</li><li>without intricacies or difficulties.</li><li>ordinary, simple, or unostentatious: Although she was a duchess, her manners were attractively plain.</li><li>with little or no embellishment, decoration, or enhancing elaboration: a plain blue suit.</li><li>without a pattern, figure, or device: a plain fabric.</li><li>not rich, highly seasoned, or elaborately prepared, as food: a plain diet.</li><li>flat or level: plain country.</li><li>Antonyms: hilly</li><li>unobstructed, clear, or open, as ground, a space, etc.</li><li>Cards. being other than a face card or a trump.</li></ul><p><strong>Adverb</strong></p><ul><li>clearly and simply: He's just plain stupid.</li></ul><p><strong>Noun</strong></p><ul><li>an area of land not significantly higher than adjacent areas and with relatively minor differences in elevation, commonly less than 500 feet (150 meters), within the area.</li><li>The Plains.</li><li>Great Plains.</li></ul>