Definition of decachord:
(n) :
A musical instrument mentioned in the Psalms, having ten strings and thought to resemble a lute or psaltery.
(n) :
(historical, music) An Ancient Greek musical instrument with ten strings, resembling the harp.
(n) :
(music) A set of ten pitches used to create a musical mode.
(n) :
Anything having ten parts, especially something of mystical Christian significance.