I. ˈsən-(ˌ)dā, -dē noun
Etymology: Middle English, from Old English sunnandæg (akin to Old High German sunnūntag ), from sunne sun + dæg day
Date: before 12th century
: the first day of the week : the Christian analogue of the Jewish Sabbath
• Sun·days -(ˌ)dāz, -dēz adverb
II. adjective
Date: 14th century
1. : of, relating to, or associated with Sunday
2.
[from the practice of wearing one's best clothes on Sunday to attend church]
: best
Sunday suit
3. : amateur
Sunday painters
III. ˈsən-dē biographical name
William Ashley 1862-1935 Billy Sunday American evangelist