Unhazardous is from un- ('not') + hazardous, from hazard, from Old French hasard ('game of dice'), perhaps from Arabic az-zahr ('the die'). Important recorded forms include un- (Old English), hasard (Old French), and az-zahr (Arabic). Morphologically, the un- element marks negation, reversal, removal, or deprivation, while the base supplies the action, quality, or state being denied or undone. The wording preserves that uncertainty: the older history is best read as a cautious account rather than a fully settled chain. The modern sense is largely compositional, with the historical elements narrowing into a stable English lexical item. In current use it covers not dangerous; safe. The wider family includes derived forms such as unhazardously and related words such as hazard and hazardous.