metamaterial

thumb|upright=1.2|Negative-index metamaterial array configuration, which was constructed of copper [[split-ring resonators and wires mounted on interlocking sheets of fiberglass circuit board. The total array consists of 3×20×20 unit cells with overall dimensions of .]]

A metamaterial (from the Greek word , meaning 'beyond' or 'after', and the Latin word , meaning 'matter' or 'material') is an engineered material whose properties arise not from the chemical composition of its base substances, but from their deliberately designed internal structure. These properties are often rare or absent in naturally occurring materials. Metamaterials are typically fashioned from multiple materials, such as metals and plastics, and arranged in repeating patterns at scales that are smaller than the wavelengths of the phenomena they influence. Their shape, geometry, size, orientation, and arrangement give them their properties of manipulating electromagnetic, acoustic, or seismic waves: by blocking, absorbing, enhancing, or bending waves, to achieve benefits that go beyond what is possible with conventional materials. Those that exhibit a negative index of refraction for particular wavelengths have been the focus of a substantial amount of research.