Definition of "Feria" :

noun: (in Spanish speaking regions) a local festival or fair, usually in honor of some patron saint

noun: 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."