Pronunciation: (ôr'gu-num), [key]
—pl. -naPronunciation: (-nu), [key] -nums.
1. an organon.
a. the doubling, or simultaneous singing, of a melody at an interval of either a fourth, a fifth, or an octave.
b. the second part in such singing.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.