the second day of the week: abbrev. Mon, Mo, or M
Origin of MondayMiddle English from Old English monandæg, moon's day from monan, genitive of mona, moon + dæg, day: translated, translation of Late Latin Lunae dies
nounAbbr. Mon. or M
The day of the week that comes after Sunday and before Tuesday. In many countries and according to international standards, Monday is considered the first day of the week.
Origin of MondayMiddle English from Old English Mōnandæg ( translation of Latin lūnae diēs day of the moon ) mōnan genitive of mōna moon ; see moon. dæg day ; see day.