Paris green

WordReference Random House Unabridged Dictionary of American English © 2026

Par′is green′, 

1. Chemistry an emerald-green, poisonous, water-insoluble powder produced from arsenic trioxide and copper acetate: used chiefly as a pigment, insecticide, and wood preservative.
2. (sometimes l.c.) a variable hue ranging from light to vivid yellow green in color.
• 1870–75

Collins Concise English Dictionary © HarperCollins Publishers::

Paris green noun

1. an emerald-green poisonous insoluble substance used as a pigment and insecticide. It is a double salt of copper arsenite and copper acetate. Formula: 3Cu(AsO₂)₂.Cu(C₂H₃O₂)₂