Definition of Great Day in US English:

Great Day

noun

Christian Church
  • 1With the. The Day of Judgement. More fully "Great Day of Judgement", "Great Day of the Lord", "Great Day of Wrath", and variants.

  • 2A very important feast day or (less commonly) day of fasting; specifically. Easter Sunday.

Origin

Late Middle English. From great + day, in sense 1 after post-classical Latin dies magnus (Vulgate).

Pronunciation

Great Day

/ˌɡreɪt ˈdeɪ/