unday
The period of time that occurs during the events of Saturday  Night and Monday (or sometimes even Tuesday) Morning that nobody has recollection of after the comedown/hangover of a big weekender. After unday, you will feel like you have lost a day that you could have legitimately used for sleeping or recovering for work/uni the next day but can't because that day seems to have dissolved into nothingness and you probably knocked yourself out for over 24 hours. 
A: *wakes up* Man I feel like shit... what time is it? we've got to go meet up with Sasha
B: That was yesterday. It's Monday today. And we're late for Uni again.
A: Shit whatever happened to sunday?
B: It's not sunday, It's Unday.

Sunrise on Friday, dPercussion on Saturday, Rave Saturday evening, Afterparty on Sunday, then it's Bank Holiday Unday.

