Refill means to fill something again after it's been emptied or used up. When you finish your glass of water at dinner, you might refill it at the sink. When a prescription runs out, your parents get a refill at the pharmacy. When your pen stops writing, you either throw it away or buy a refill cartridge to make it work again.

The word appears everywhere in daily life. Gas stations have signs about free refills on soft drinks. Restaurants offer unlimited refills on coffee or iced tea. Teachers refill the paper tray in the classroom printer. Gardeners refill bird feeders when they're empty.

Notice that refill can work as both a verb and a noun. You refill your water bottle (verb), or you ask for a refill of popcorn at the movies (noun). The word reminds us that many things we use aren't meant to be thrown away after one use. A reusable water bottle you refill every day is better for the environment than buying dozens of disposable plastic bottles.