(bonYs ) Word forms: plural bonuses. 1. countable noun. A bonus is an extra amount of money that is added to someone's pay, usually because they have worked very hard.

BONUS | definition in the Cambridge English Dictionary.

A promotion intended to increase trading volume and overall revenue of the client. Bonus funds support account margin and can be withdrawn after completing bonus amount/2 standard lots.

"100%" - this means that you'll receive a bonus amount equal to your first deposit. e.g. deposit $100 and get another $100 extra as bonus money.