The story
From Eupenicillium brefeldianum (a fungus in which it is found) + -in.
Etymology from Wiktionary, CC BY-SA 4.0.
brefeldin A
Today it means: A lactone antibiotic produced by fungal organisms such as Eupenicillium brefeldianum, inhibiting transport of proteins from ER to Golgi and inducing retrograde protein transport from the Golgi apparatus to the endoplasmic reticulum. Full definition →