Sunday
Old English Sunnandæg ‘day of the sun’, translation of Latin dies solis . Compare with Dutch zondag and German Sonntag .
wiktionary
From Middle English Sonday, from Old English sunnandæġ(“day of the sun”), from sunne(“sun”), + dæġ(“day”), from Proto-West Germanic *sunnōn dag, as a translation ( interpretātiō germānica) of Latin diēs Sōlis; declared the "venerable day of the sun" by Roman Emperor Constantine on March 7, 321 C.E..
Compare Saterland Frisian Sundai(“Sunday”), German Low German Sünndag, Dutch zondag, West Frisian snein, German Sonntag, Danish søndag.
etymonline
Sunday (n.)
first day of the week, Old English sunnandæg (Northumbrian sunnadæg), literally "day of the sun," from sunnan, oblique case of sunne "sun" (see sun (n.)) + dæg "day" (see day). A Germanic loan-translation of Latin dies solis "day of the sun," which is itself a loan-translation of Greek hēmera heliou. Compare Old Saxon sunnun dag, Old Frisian sunnandei, Old Norse sunnundagr, Dutch zondag, German Sonntag "Sunday."
In European Christian cultures outside Germanic often with a name meaning "the Lord's Day" (Latin Dominica). Sunday-school dates from 1783 (originally for secular instruction); Sunday clothes is from 1640s. Sunday driver is from 1925.
