Five Card Omaha
It's what you'd think: Omaha High Only, but with five hole cards instead of four. It's high only1.
Like regular Omaha High, at the showdown, each player must use exactly two hole cards and three from the board. It is typically played Pot-Limit, but can also be played Fixed-Limit or No-Limit.
1
The High/Low (with eight qualifier) variant is called Big O.