(uncountable) The condition of being plain (in all senses) / (countable) The product or result of being plain

plural of plainness

(US, with "the") The Great Plains region of North America. / A ghost town in California. / A town in Georgia, North America. / A city in Kansas. / A town in Montana.

(colloquial) Simply. / (archaic) Plainly; distinctly.

(rare, poetic) A lamentation.

(now rare, regional) Flat, level. / Ordinary; lacking adornment or ornamentation; unembellished. / Of just one colour; lacking a pattern.

(obsolete) Full, complete in number or extent.

(obsolete, transitive) To level; to raze; to make plain or even on the surface. / (obsolete, transitive) To make plain or manifest; to explain.

An expanse of land with relatively low relief, usually exclusive of forests, deserts, and wastelands. / (archaic) Synonym of field in reference to a battlefield.

(reflexive, obsolete) To complain. / (transitive, intransitive, now rare, poetic) To lament, bewail.