Fasting and week-day names

Do you speak Irish? Maybe you know several Irish words? I don't know a word in Irish myself but I've just learned one curious thing: the days of the week Wednesday and Friday are called fasting and Thursday is the day between fastings. Wow! In the Orthodox Christian tradition Wednesday and Friday were banian days as well, although in Russian the meaning of the names is different (Wednesday sreda means middle, Friday pyatnitsa means the fifth day of the week).