1) Ancient Greek music 
Pyknon, πυκνόν, sometimes also transliterated as pycnon (from πυκνός close, close-packed, crowded, condensed; spissus) in the music theory of Antiquity is a structural property of any tetrachord in which a composite of two smaller intervals is less than the remaining (incomposite) interval. The makeup of the pyknon serves to identify t...