Where does “des-” come from?

des- (Old Portuguese) comes from Latin dis-, from Latin calceus, from Latin calx, from Ancient Greek χάλιξ — small stone, pebble; gravel, rubble.

Ancestry of “des-”, step by step

Step	Language	Word	Meaning
1	Latin	dis-	asunder, apart, in two; reversal, removal;...
2	Latin	calceus	shoe
3	Latin	calx	limestone; chalk; the finish line
4	Ancient Greek	χάλιξ	small stone, pebble; gravel, rubble