Where does “poyson” come from?

poyson (Middle English) comes from Old French poison, from Latin pōtiō, from Latin -tiō, from Latin dissertātiō, from Latin dissertus, from Latin disserere, from Latin dis-, from Latin calceus — small stone, pebble; gravel, rubble.

Ancestry of “poyson”, step by step

poyson traces back through two separate lines of ancestry.

via Old French poison

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

via Old French puison

Step	Language	Word	Meaning
1	Old French	puison	—
2	Latin	potio	drinking; drink, draught, potion
3	Latin	potare	present active infinitive of pōtō; second-person...
4	Latin	poto	I drink

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