fast day

1. 1.

   a day designated for fasting

   Broaderreligious holiday

   Narrowermajor fast dayminor fast day

Questions about fast day

What does fast day mean?

fast day means "a day designated for fasting".

Is fast day a common word?

fast day is banded "Uncommon" — turns up in careful writing rather than conversation. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.