1. To set aside, keep back, or save something for someone, something, or some future point or event. You should always reserve some of your income for an emergency. Sorry, I'm reserving this seat for a friend. Be sure to reserve a cup of the pasta's cooking water for your sauce.

2. To instruct or request for something to be set aside for someone, something, or some future point or event. I reserved a table for us at the restaurant tonight. We reserved the conference room for our meeting. I've reserved the bikes for the next three days.