max
The greatest amount or level something can reach.
Max is short for maximum, meaning the greatest amount possible or allowed. When a video game character's health bar is at max, they're at full strength. When your teacher says “five pages max” for an essay, they mean you can't write more than five pages.
The word shows up constantly in everyday life. A sign saying “max capacity: 20 people” means the room can't safely hold more than twenty. When you turn the volume to max, you've cranked it as high as it goes. Athletes talk about maxing out when they lift the heaviest weight they possibly can or push themselves to their absolute limit.
Max can also be a verb. To max something out means to reach its upper limit: you might max out your library card by borrowing as many books as the rules allow, or max out a video game skill tree by unlocking every possible upgrade.
People also use to the max as a phrase meaning “to the greatest degree possible.” If someone decorates their room to the max, they've gone all out with posters, lights, and everything they can think of. It's the opposite of holding back or doing something halfway.