The story
From Haematoxylum (“genus of the logwood tree”) + -in.
Etymology from Wiktionary, CC BY-SA 4.0.
hematoxylin
Today it means: A phenolic compound having the chemical formula C₁₆H₁₄O₆, used (most often in conjunction with eosin) to make dye for staining tissue samples; extracted from the heart of bloodwood trees (Haematoxylum campechianum). Full definition →