Feria
WordNet
noun
(1) (in Spanish speaking regions) a local festival or fair, usually in honor of some patron saint
(2) A weekday on which no festival or holiday is celebrated
"In the middle ages feria was used with a prefixed ordinal number to designate the day of the week, so `secunda feria' meant Monday, but Sunday and Saturday were always called by their names, Dominicus and Sabbatum, and so feria came to mean an ordinary weekday"