Where does “empoisonneur” come from?

empoisonneur (French) comes from French empoisonner, from French poison, from Old French poison, from Latin pōtiō, from Latin -tiō, from Latin dissertātiō, from Latin dissertus, from Latin disserere — small stone, pebble; gravel, rubble.

empoisonneur (French): poisoner

Definitions

poisoner

Ancestry of “empoisonneur”, step by step

Step	Language	Word	Meaning
1	French	empoisonner	to poison, to kill by poisoning
2	French	poison	poison
3	Old French	poison	poison; potion
4	Latin	pōtiō	drinking
5	Latin	-tiō	tion, -ation, -ing
6	Latin	dissertātiō	(spoken) dissertation, discourse, disquisition
7	Latin	dissertus	arranged, disposed; explained
8	Latin	disserere	second-person singular future passive indicative...
9	Latin	dis-	asunder, apart, in two; reversal, removal;...
10	Latin	calceus	shoe
11	Latin	calx	limestone; chalk; the finish line
12	Ancient Greek	χάλιξ	small stone, pebble; gravel, rubble

Every word from Ancient Greek χάλιξ →Every word from Latin -tiō →Every word from Latin dis- →