The story
From benz(yl)pyr(id)ine + -ium (“quaternary ammonium compound”).
Etymology from Wiktionary, CC BY-SA 4.0.
benzpyrinium
Today it means: The pyridinium cation 1-benzylpyridin-1-ium-3-yl N,N-dimethylcarbamate, the bromide of which is used to relieve postoperative urinary retention. Full definition →