Etymology: < Anglo-Norman and Middle French accident (French accident ) unfortunate occurrence or incident, vicissitude of fortune, indication, exterior sign, symptom (all 12th cent. in Anglo-Norman or Old French), chance occurrence (13th cent.), non-essential quality, (of a word) grammatical property, morphological variation (all 14th cent.) and its etymon classical Latin accident-, accidēns accidental happening, chance event, contingency, circumstance, (in grammar and rhetoric) attribute, in post-classical Latin also (in theology and philosophy) contingent attribute (3rd cent.), symptom (c400), grammatical property, morphological variation, adjective (5th cent.: see note), use as noun of present participle of accidere to fall, to happen < ac- ac- prefix + cadere to fall (see cadence n.). Compare Old Occitan accident , Catalan accident (13th cent.), Spanish accidente (13th cent.), Portuguese acidente (14th cent.), Italian accidente (13th cent.). Compare also post-classical Latin accidentia accidence n.¹The earliest instances of classical Latin accidēns in sense ‘attribute’ are in Quintilian, twice explicitly rendering ancient Greek συμβεβηκός as used (sometimes in contrast with οὐσία ‘substance’) in the rhetorical writings of Hermagoras and Theodorus of Gadara. The Greek word had been used in Aristotle (e.g. Metaphysics 1052^a18, 1052^a31) as a philosophical term denoting a contingent attribute, or an attribute necessarily resulting from the notion of something, but not entering into its definition; Christian Latin writers from Tertullian onwards use accidens in the former of these philosophical senses (more or less precisely, and with various refinements in scholastic writings), often in contrast with substantia substance n. Post-classical Latin accidens came to be used for ‘adjective’ because non-essential attributes are naturally indicated with adjectives (see Quintilian 8. 3. 70 and Priscian 2. 83. 18). Compare also accidence n.² and discussion at that entry. Compare the following attestations in an English context of Latin accidentia , use as noun of the neuter nominative plural of accidens , denoting a type of adjective, and in sense ‘grammatical properties’ (compare sense 3):OE Ælfric Gram. (St. John's Oxf.) 12 Sume [naman] synd accidentia, þæt synt gelimplice, þe gelimpað anum gehwylcum: niger coruus blac hrem, profundum mare deop sæ.OE Ælfric Gram. (St. John's Oxf.) 92 Ðes dæl, þæt is pronomen, hæfð syx accidentia, þæt synd [syx] gelimp: him belimpþ species, þæt is, hiw; persona, þæt is, had; and genvs, þæt is, cynn; and figvra, þæt is, anfeald hiw oððe gefeged; and nvmervs, þæt is, getel; and casvs gebigednyss.

Etymology: < Middle French accident (in medicine) following in the course of an illness (14th cent.), non-essential (15th cent.), and its etymon classical Latin accident-, accidens accidental, non-essential, in post-classical Latin also happening by chance (4th cent.), use as adjective of present participle of accidere (see accident n.). Compare earlier accidental adj.