Plural of commonplace; ordinary or trite ideas, statements, or situations that lack originality; also, entries in a commonplace book.
From 'commonplace' (plural form). In early usage, 'commonplaces' referred to collections of useful, shared knowledge; the meaning shifted to emphasize their ordinariness.
When Shakespeare made Romeo and Juliet use the most romantic language imaginable, he was subverting 'commonplaces'—love poetry had become so predictable that making it familiar actually highlighted how artificial courtly love had become.
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