v.1. To draw off or convey something through or as if through a siphon: I used a tube to siphon off the excess water in the fish tank. The lawn mower ran out of gas, so we siphoned some off from the car's gas tank.
2. To appropriate some money illegally or dishonestly: The managers were siphoning off money from the foundation and putting it into secret accounts. The dictator siphoned millions of dollars off and hid the money in private bank accounts.