Mobile means able to move or be moved easily from place to place. A mobile library might travel from neighborhood to neighborhood in a van, bringing books to people who can't easily get to a regular library. During a storm, you want to keep your bike and other mobile objects secured so they don't blow away.

When something is mobile, it has freedom of movement. Wildlife biologists study how mobile different animals are: a deer is highly mobile and might roam many miles in a day, while a turtle moves more slowly but is still mobile. Someone who breaks their leg might lose mobility temporarily and need crutches to stay mobile.

The word also describes things designed to be portable. A mobile phone (often just called a mobile) goes with you wherever you travel, unlike the landline phones that stayed attached to walls in houses. Mobile homes are houses built to be transported on trucks, though most stay in one spot once positioned.

You might also see a mobile hanging from a ceiling: a decoration with shapes suspended on strings or wires that move and spin in air currents. The sculptor Alexander Calder became famous for creating artistic mobiles.

In another context, mobile can describe someone's face when it's expressive and animated, with features that move easily to show different emotions.