menstruum
Concise Oxford English Dictionary © 2008 Oxford University Press:
menstruum /ˈmɛnstrʊəm/
▶noun (pl. menstrua /-strʊə/)
- 1 menses.
- 2 archaic a solvent.
– origin ME: from L., neut. of menstruus ‘monthly’, from mensis ‘month’; sense 2 is by alchemical analogy between transmutation of metals into gold and the supposed action of menses on the ovum.
'menstruum' also found in these Oxford entries:

