Rollover is a term linked with a betting bonus to describe the amount you need to wager (playthrough) to change the balance from your bonus into withdrawable cash. Most betting bonuses will have a rollover attached and it's imperative you know how it works before you claim an offer.
Most pre-retirement payments you receive from a retirement plan or IRA can be rolled over  by depositing the payment in another retirement plan or IRA within 60 days. You can also have your financial institution or plan directly transfer the payment to another plan or IRA.