Lewis Short
(adj.Subst.) = τετράχορδος, ον,: tētrăchordos, on, adj.
* Having four strings or notes.
* Adj.: machina,a water-organ,Vitr. 10, 13.
* Subst.tētrăchordon (-dum), i, n., a chord of four notes, a tetrachord.
* Lit., Vitr. 5, 4; Mart. Cap. 9, §§ 935 and 941; Macr. S. 1, 19 med.
* Trop.: anni, i. e. the four seasons, Varr ap. Non. 71, 16.
Charlton T. Lewis, Charles Short, A Latin Dictionary