Definition of Millon's base in US English:

Millon's base

noun

Biochemistry Chemistry
  • A yellow basic powder, Hg₂NOH·2H₂O, produced by the action of aqueous ammonia on mercuric oxide (as reported by Millon in Ann. de Chim. et de Physique (1846) 18 393).

Origin

Late 19th century; earliest use found in Encyclopaedia Britannica.