Mon"day (mŭn"d?; 48), n. [OE. moneday, monenday, AS. mōnandæg, i.e., day of the moon, day sacred to the moon; akin to D. maandag, G. montag, OHG. mānatag, Icel. mānadagr, Dan. mandag, Sw. måndag. See Moon, and Day.] The second day of the week; the day following Sunday.

-- Webster's unabridged 1913