Zenkai is the power boost that a Saiyan receives once he/she has experienced near
death. In the Dragon Ball franchise, this can best be seen when Vegeta receives a large enough boost to over-power Zarbon, an enemy who had beaten him only a few episodes before.
In a much less literal
definition, anyone can experience Zenkai. It's just when someone comes back stronger and better than ever from a bad L taken in
life. We all have Zenkai.
Person 1: Damn
bro I heard Laura rejected you the other day.
Person 2: It's
all good man, my Zenkai is kicking in. I'll
just hook up with her best friend.