noun the second day of the week; the first working day
Mon.
WordNet
Mon"day noun
Etymology
OE. moneday, monenday, AS. monandæg, i.e., day of the moon, day sacred to the moon; akin to D. maandag, G. montag, OHG. manatag, Icel. manadagr, Dan. mandag, Sw. måndag. See Moon, and Day.
Definitions
The second day of the week; the day following Sunday.