n. The quality of being perspicuous or transparent; that quality of a substance which renders objects visible through it; transparency; clearness.n. The quality of being clear to the mind, or easily apprehended or understood; clearness to mental vision; freedom from obsurity or ambiguity; that quality of writing or language which readily presents to the mind of another the precise ideas of the author; clearness.n. Synonyms Perspicuity, Lucidity, Clearness, Plainness. These words, as expressing a quality of style, suggest much of their original meaning. Perspicuity is the quality by which the meaning can be see through the words, transparency. Lucidity expresses the same idea, or the other meaning of lucid, that of the radiation or shining forth of the idea from language. Clearness may have two aspects, corresponding to the clearness with which one sees an object as separate from other things, or to the clearness of water when it is not darkened in any way. plainness rests upon the idea that nothing rises up to intercept one's view of the thought; it therefore implies, as the others do not, a simpler and homelier diction, etc. Clearness or perspicuity is the common heading for that department of rhetoric which treats of intelligibility in methods of expression.