an event, undertaking, or item that seems promising but turns out to be nothing like what you imagined.
Our relationship was an upstart, she seemed really great at the beginning but it turned out she was boring and lame.
by finnegan October 17, 2005
UpStart (uhp-stahrt) n. 1. A company or organization with innovative approaches to energy use, carbon pollution, resource consumption, and/or social equity, 2. A company or organization overcoming market barriers to build the new clean energy economy.

Coined by Lisbeth Kaufman as the title of a column on Climate Progress.
“UpStarts” are companies that are shaking up the market, breaking down barriers and helping change the economy.
by UpStarter June 3, 2011
The upstart knockoff effect is when a character appears that closely resembles a pre-existing character. When this happens, the previous character appears less important.

Definition source: The anime Needless - Episode 5.
Come on then if you think you can take me on, you upstart knockoff
by anime watcher April 27, 2013
An AI lending platform that partners with banks and credit unions to provide consumer loans using non-traditional variables, such as education and employment, to predict creditworthiness.
"What do they do, I don't even know em?"..."uhh excuse me?"...."What does Upstart Holdings Inc do?"...."Uhh well, um, um, um I'm sorry."..."What kind of company is it?"...."yeah, um, you're breaking up", *Curb your enthusiasm theme song plays*.
by PuruSaxena October 18, 2021