Mrs Grundy is a figurative name for an extremely conventional or priggish person,[1] a personification of the tyranny of conventional propriety.[2] A tendency to be overly fearful of what others might think is sometimes referred to as grundyism.
Mrs Grundy originated as an unseen character in Thomas Morton's 1798 five-act comedy Speed the Plough.[2] References to Mrs Grundy were eventually so well established in the public imagination that in Samuel Butler's 1872 novel Erewhon, the goddess Ydgrun, an anagram for Grundy, dictates social norms. As a figure of speech, "Mrs Grundy" can be found throughout the English-speaking world.