Mon ‧ day /ˈmʌndi, -deɪ/ BrE AmE noun [uncountable and countable] ( written abbreviation Mon. )
[ Language: Old English ; Origin: monandæg , from a translation of Latin lunae dies 'day of the moon' ]
the day between Sunday and Tuesday
on Monday
It was raining on Monday.
The president announced Monday that he would cancel the debt.
American English
Monday morning/afternoon etc
Let’s go out for a meal on Monday night.
last Monday
Kelly arrived last Monday.
this Monday
The UK office will open for business this Monday.
next Monday (=Monday of next week)
Shall we meet next Monday?
a Monday (=one of the Mondays in the year)
My birthday’s on a Monday this year.