plainnessn.
'plennɪs
中文n. 明白；平坦；正直；平坦度
词根词源
plainness (n.)c. 1300, "flatness," from plain (adj.) + -ness. Meaning "clarity" is mid-15c.; that of "open conduct" is from 1540s; that of "absence of ornament" is from 1580s.
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