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Webster 1913 Edition

Red-letter

Red′-letˊter

(-l?tˊt?r)
,
Adj.
Of or pertaining to a red letter; marked by red letters.
Red-letter day
,
a day that is fortunate or auspicious; – so called in allusion to the custom of marking holy days, or saints’ days, in the old calendars with red letters.

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