a day on which fasting is observed, especially such a day appointed by some ecclesiastical or civil authority.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use fast day in a sentence
When he came to Ayno, he found the Doctor just gone to Church, it being observed by him and his people as a fast-day.Memorials of the Independent Churches in Northamptonshire | Thomas Coleman
The governor and council had appointed a fast-day to be kept through the country upon Good-Friday for the success of the king.Great Events in the History of North and South America | Charles A. Goodrich
On the fast-day fists were shaken at Mr. Dishart as he walked sternly homeward, but he was undismayed.Auld Licht Idyls | J. M. Barrie
Instead of this incident's humbling Tilliedrum into attending church, the next fast-day saw its streets deserted.Auld Licht Idyls | J. M. Barrie
Forgotten the torturing heat, forgotten the hunger and thirst of the fast day!Simon Eichelkatz; The Patriarch | Ulrich Frank