Modifiers matching circumstance:

• exceptional,
• unexpected,
• personal,
• unfortunate,
• unforeseen,
• threatening,
• unforeseeable,
• catastrophic,
• negative,
• stressful,
• involuntary,
• external,
• bad,
• common,
• extraordinary,
• unusual,
• individual,
• extreme,
• unique,
• severe,
• exigent,
• verifiable,
• relevant,
• unavoidable,
• special,
• historical,

Simple categories matching unforeseen:

• event,
• circumstances,
• expense,
• development,
• consequence,
• happening,
• force,
• incident,
• case,
• situation,
• crisis,
• difficulty,
• adversity,
• occurrence,
• shock,
• disturbance,
• cataclysm,
• hazard,
• work,
• accident,
• misfortune,
• disaster,
• circumstance,
• problem,
• thing,
• weather,
• catastrophe,
• charge,
• contingency,
• condition,
• eventuality,
• expenditure,
• emergency,
• trouble,
• setback,
• calamity,