is a specific kind of: event.

is a broader term that covers: accompaniment, attendant, co-occurrence, concomitant | avalanche | experience | trouble | treat | miracle | marvel, wonder | thing | episode | contingence, contingency, eventuality | beginning | conclusion, ending, finish | one-off | periodic event, recurrent event | alteration, change, modification | computer error, error | accident, chance event, fortuity, stroke | fire | incident | discharge | case, example, instance | motion, movement | failure | success | appearance | destiny, fate | disappearance | disappearance | contact, impinging, striking | finish | collapse | break, interruption | sound | union | news event | flash | convergence | juncture, occasion | burst, flare-up, outburst | eruption, irruption, outbreak | black eye, blow, reversal, reverse, setback | bonanza, boom, bunce, godsend, gold rush, gravy, manna from heaven, windfall | collapse, crash | supervention ... show more.

derivation: come about, fall out, go on, hap, happen, occur, pass, pass off, take place | occurrent.