tetra-

from The Century Dictionary.

• noun A prefix in compounds derived from the Greek, signifying ‘four’: as, tetrachord, tetragon, tetrarch, tetramerous, tetrapetalous, tetraspermous.

from the GNU version of the Collaborative International Dictionary of English.

• A combining form or prefix signifying four, as in tetrabasic, tetrapetalous.
• (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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• prefix Forming compound words having the sense of ‘four’.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun brightly colored tropical freshwater fishes