Tetra- /(?)/

Tet·ra-

Tetra-
  1. A combining form or prefix signifying four, as in tetrabasic, tetrapetalous.
  2. A combining form (also used adjectively) denoting four proportional or combining parts of the substance or ingredient denoted by the term to which it is prefixed, as in tetra-chloride, tetroxide. (Chem.)