天癸

天癸	tiān guǐ	(TCM) menstruation / period
天	tiān	day / sky / heaven
癸	guǐ	tenth of the ten Heavenly Stems 十天干 / tenth in order / letter "J" or Roman "X" in list "A, B, C", or "I, II, III" etc / ancient Chinese compass point: 15° / deca