ELI5: Explain Like I'm 5

Metamaterial

Metamaterials are materials which are made of special structures that are much smaller than the wavelengths of light. These structures are often called meta-atoms and are arranged in a pattern to give the material special properties that it wouldn't naturally have, such as the ability to bend or control light. This means that metamaterials can be used to make things that don't exist in nature, like special lenses or antennas for phones.