(rare, poetic) A lamentation.

An expanse of land with relatively low relief, usually exclusive of forests, deserts, and wastelands.

(transitive, intransitive, now rare, poetic) To lament, bewail.

(now rare, regional) Flat, level.

An ordinary, unadorned, simple adjective that can describe something lacking ornamentation, lacking a pattern, unsophisticated, lacking additional ingredients or seasonings, or containing no extended or nonprinting characters in computing.

An adjective "plain" is evident, clear, and unmistakable, or it can be used as an intensifier to mean downright or total.

A plain adjective is honest, clear, unencumbered, equal, fair, and without deception.

Not unusually beautiful; unattractive.

(card games) Not a trump.

(colloquial) Simply.