c.1600, from Fr. explicite, from L. explicitus, variant pp. of explicare "unfold, unravel, explain," from ex- "out" + plicare "to fold" see ply (v.)). "Explicitus" was written at the end of medieval books, originally short for explicitus est liber "the book is unrolled." As a euphemism for "pornographic" it dates from 1971.