There are currently 9 names in this directory beginning with the letter O.
When the first person to enter the pot preflop does so by just calling the big blind, rather than raising.
When the first person to put money in the pot preflop does so by raising. Also known as an open.
When action folds or limps to the small blind, and the small blind calls, the big blind has the 'option' of checking or raising.
The number of hands it takes for each person to be the button once. In a 9-handed game an orbit is 9 hands.