self; oneself; sixth of the ten Heavenly Stems 十天干[shi2 tian1 gan1]; s
Origin unclear. Possibly a pictograph of a silk rope, in which case would be the original form of 紀.
《說文》：“己，中宮也，象萬物辟藏詘形也。己承戊，象人腹，，古文己。”