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Phrase(s): till the fat lady sings [and] when the fat lady sings
Fig. at the end; a long time from now. (Supposedly from a tale about a child—sitting through an opera—who asks a parent when it will be over. "Not until the fat lady sings" is the answer.) • Relax. It won’t be over till the fat lady sings. • We can leave with everybody else when the fat lady sings.
McGrawhill's American Idioms And Phrasal Verbs