sunday Meaning, Definition & Usage

  1. noun first day of the week; observed as a day of rest and worship by most Christians
    Sun; Dominicus; Lord's Day.
  2. noun United States evangelist (1862-1935)
    Billy Sunday; William Ashley Sunday.

WordNet

Sun"day noun
Etymology
AS. sunnandæg; sunne, gen. sunnan, the sun + dæg day; akin to D. zondag, G. sonntag; -- so called because this day was anciently dedicated to the sun, or to its worship. See Sun, and Day.
Definitions
  1. The first day of the week, -- consecrated among Christians to rest from secular employments, and to religious worship; the Christian Sabbath; the Lord's Day. Syn. -- See Sabbath.
Sun"day adjective
Definitions
  1. Belonging to the Christian Sabbath.

Webster 1913