subs. phr. (common).—An unlimited period: hence ONCE IN A BLUE MOON = extremely seldom: see QUEEN DICK.

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  1528.  ROY and BARLOW, Rede me and be nott wrothe, 114 [ed. ARBER, 1871].

        Yf they saye the MONE IS BELEWE,
We must beleve that it is true,
  Admittynge their interpretacion.

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  1860.  F. W. ROBINSON, Grandmother’s Money, I., 144. If he talked till a BLUE MOON, etc.

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  1876.  M. E. BRADDON, Joshua Haggard’s Daughter, xxiv. Why should she stint as to one or two puddings a week … and a fruit pasty ONCE IN A BLUE MOON.

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  1884.  R. E. FRANCILLON, Ropes of Sand, xxi. ‘I’ve made bold to take the chance of your being at home for ONCE IN A BLUE MOON, Mr. Carew,’ said she.

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  1901.  People, 7 April, 13, 1. As a matter of fact, some of the inmates have a bath ONCE IN A BLUE MOON, and give their faces and hands a cat-lick once a week.

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