in classical prosody, a period made up of four colons, or a unit of four metrical sequences that each constitute a single metrical phrase of not more ... Found on http://www.britannica.com/eb/a-z/t/30
Tet`ra·co'lon noun [ Greek ... with four members; te`tra- (see Tetra- ) + ... limb, member.] (Pros.) A stanza or division in lyric poetry, consisting of four verses or lines. Crabb. Found on http://www.encyclo.co.uk/webster/T/34