Definition of orbit
What is meant by orbit to poker is a complete round. It is the same vocabulary in tournament play as in games of cash games as in sit’n’go. The number of seats will not matter. Tournament players sometimes calculate their mats in orbits rounds. For example, if you have a 10,000 chip stack and the blinds are 500/1000, you can tell yourself that you have 10 big blinds, but you can also calculate that you will have roughly 6 orbits left before you are blinded (making blind is being cheated out of your stack by the blinds). Instead of saying that you have a carpet of 10 big blinds, you will say that you have a carpet allowing you to make 6 turns of orbit.
Other details about the orbit
The orbit does not have to be a specific number of hands. Whether the table has 6, 9 or 10 players, when all the players have been once on each position, we will talk about an orbit. On a poker table, each position has its own particularity (some are very powerful like the button position, others much less advantageous like the small blind) and that is why, in turn, the positions will change. When each player has been on each position once, we will talk about an orbit.