tetra : Idioms & Phrases

• noun small bright red and blue aquarium fish from streams in Brazil and Colombia
  Paracheirodon axelrodi.
  

WordNet

Tet"ra-

Etymology

Gr. , from , , four. See Four.

Definitions

1. A combining form or prefix signifying four, as in tetrabasic, tetrapetalous.
2. (Chem.) 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.

Webster 1913