n. & adv.
n. 1 the first day of the week, a Christian holiday and day of worship. 2 a newspaper published on a Sunday.
adv. colloq. 1 on Sunday. 2 (Sundays) on Sunday; each Sunday. Sunday best joc. a person's best clothes, kept for Sunday use. Sunday letter = dominical letter. Sunday painter an amateur painter, esp. one with little training. Sunday school a school for the religious instruction of children on Sundays.
[ OE sunnandg, transl. of L dies solis, Gk hemera heliou day of the sun ]