To rely on a future occurrence (even though it might not happen). I've really been banking on a holiday bonus this year—I don't have enough money to buy presents without it.I don't think you can bank on Tom coming tonight—he's really unreliable.
Fig. to be so sure of something that one can trust it as one might trust a bank with one's money. I will be there on time. You can bank on it.I need a promise of your help. I hope I can bank on it.
Rely on, count on. For example, You can bank on Molly's caterer to do a good job. This expression alludes to bank as a reliable storage place for money. [Late 1800s]