Most dictionaries consider the etymology of these Italian terms uncertain, but some suggest they perhaps come fromVulgar Latin*resecum(“that which cuts, rock, crag”) (>Medieval Latinresicu), fromLatinresecō(“cut off, loose, curtail”,verb), in the sense of that which is a danger to boating or shipping; or fromAncient Greekῥιζικόν(rhizikón,“root, radical, hazard”).
A few dictionaries express more certainty. Collins says the Italianrisco comes fromAncient Greekῥίζα(rhíza,“cliff”) due to the hazards of sailing along rocky coasts. The American Heritage says it probably comes fromByzantine Greekῥιζικό, ριζικό(rhizikó, rizikó,“sustenance obtained by a soldier through his own initiative, fortune”), fromArabicرِزْق(rizq,“sustenance, that which God allots”), fromClassical Syriacܪܘܙܝܩܐ ,ܪܙܩܐ(rezqā, rōzīqā,“daily ration”), fromMiddle Persian[script needed](rōčig), fromMiddle Persian[script needed](rōč,“day”), fromOld Persian[script needed](*raučah-), fromProto-Indo-European*lewk-. Karla Mallette derives the word fromArabicرِزْق(rizq,“sustenance, that which God allots”) viaSabir.[1]
Cognate withSpanishriesgo,Portugueserisco