Ordinary; common: a period when labor strikes were commonplace. Uninteresting; unremarkable:"his disappointment at finding his child so commonplace"(Jane Stevenson). A trite or obvious saying; a platitude:"the solidified commonplaces of established wisdom"(John Simon). Something, especially an occurrence, that is ordinary or common:"These stories dealt only with the commonplaces of life"(Jack London). Archaic A passage marked for reference or entered in a commonplace book.