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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.
1. To save a particular resource or thing so as to have it in reserve. A noun or pronoun can be used between "bank" and "up." Are we allowed to bank up sick time at this company?
2. To form something into a mound or pile supported by something else. A noun or pronoun can be used between "bank" and "up." Hey, bank those leaves up against the shed.
3. To form something into a mound or pile as a means of protection. A noun or pronoun can be used between "bank" and "up." We banked up some old bricks to hide from the invaders.
bank on something
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.
bank something up(against something)
1. to heap or mound up something so that it presses against something. Walter banked the coals up against the side of the furnace. He banked up the coals against the side. Tim banked the coals up.
2. to heap or mound up something to guard against something. They had to build barriers to hide behind. They banked dirt and rubble up against the oncoming attackers. Who banked up this dirt against the flood? The river was rising, so we banked some dirt up.
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]
To rely on someone or something: You can bank on her to get the job done when it has to be done quickly. I wouldn't bank on the bus arriving on time.