Mawson, C.O.S., ed. (1870–1938). Roget’s International Thesaurus. 1922.

Class IV. Words Relating to the Intellectual Faculties
Division (II) Communication of Ideas
Section III. Means of Communicating Ideas
Various Qualities of Style

570. Perspicuity.

   NOUN:PERSPICUITY (intelligibility) [See Intelligibility]; plain speaking (manifestation) [See Manifestation]; definiteness, definition; exactness [See Truth]; explicitness, lucidness, lucidity, limpidity, clearness.
   ADJECTIVE:LUCID (intelligible) [See Intelligibility]; limpid, pellucid, clear; explicit (manifest) [See Manifestation]; exact [See Truth].
   QUOTATION:Clear conception leads naturally to clear and correct expression.—Boileau