tetra-

CIDE DICTIONARY

tetra-,  [Gr. te`tra-, from te`sares, te`ttares, four. See Four.].

•  A combining form or prefix signifying four, as in tetrabasic, tetrapetalous.  [1913 Webster]
•  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.  [1913 Webster]

OXFORD DICTIONARY

tetra-, comb. form (also tetr- before a vowel)
1 four (tetrapod).
2 Chem. (forming names of compounds) containing four atoms or groups of a specified kind (tetroxide).

Etymology

Gk f. tettares four