look up any word, like oprah dollars:
 
1.
Someone who will never notice you.
Wow! I hope senpai notices me this year!
by Senpai August 15, 2012
 
2.
(Japanese)An Upperclassman. Used in relation to fellow classmates of higher level or age. It can be used like -chan or -san as well as by itseld. I.E.: "Urameshi-senpai" or just "senpai"
"Sempai! You're going to be later for class!"
by Sashiro September 27, 2004
 
3.
It originates from anime and manga. It's someone older than you. Someone you look up to. If they give the slightest attention to you, you sort of explode. They are just really admired by you and if you are a senpai, bask in it!
"Senpai actually said hi to me today!"
by bonerdict-cumberbatch July 01, 2013
 
4.
any anme-senpai. In Japan it means my comrad of higher class, but not that much higher
Hiiro-senpai=Hiiro of higher classness
by Nasyki February 28, 2004