metamaterial

Short definition from Wiktionary

Noun

1. 1
   Any material engineered to have a property that is rarely observed in naturally occurring materials; especially
2. 2
   Any material engineered to have a property that is rarely observed in naturally occurring materials; especially: Any material that obtains its electromagnetic properties from its structure rather than from its chemical composition; especially a material engineered to have features of a size less than that of the wavelength of a class of electromagnetic radiation.