To remain means to stay in the same place, condition, or state when other things change or leave. When your friends head home but you remain at the park, you're choosing to stay behind. When snow remains on the ground after a storm, it hasn't melted yet.

The word often implies persistence or continuation over time. Ancient Roman ruins remain in Italy thousands of years after they were built. A mystery remains unsolved when detectives still haven't figured it out. Your best friend might remain loyal even when others aren't.

Remain can also describe what's left over. If you eat most of your pizza but save two slices for later, those slices are the remaining pieces. The remainder is what's left after everything else is gone or used up. In math, the remainder is what's left over after division that doesn't divide evenly.

Sometimes remaining takes strength. A lighthouse remains standing through fierce storms. A person's courage can remain strong during difficult times. When someone tells you to remain calm during an emergency, they're asking you to keep your composure when everything around you feels chaotic. Remaining can mean holding steady when it would be easier to change, leave, or give up.