Modifiers matching antigen:

• possible,
• endogenous,
• foreign,
• dangerous,
• exogenous,
• microbial,
• extrinsic,
• oral,
• outdoor,
• harmless,
• environmental,
• strong,
• diverse,
• peripheral,
• main,
• soluble,
• bacterial,
• free,
• outside,
• viral,
• harmful,
• proteinaceous,
• particulate,
• single,
• infectious,
• internal,
• nutritional,
• noninfectious,
• lethal,
• indoor,
• perennial,
• active,
• innocuous,
• small,
• simple,
• several,
• extraneous,

Simple categories matching possible:

• artifact,
• feature,
• piece,
• cause,
• infection,
• activity,
• reaction,
• condition,
• contaminant,
• defect,
• symptom,
• work,
• organism,
• theme,
• toxin,
• situation,
• action,
• service,
• toxicant,
• catalyst,
• material,
• nexus,
• disease,
• way,
• evidence,
• disorder,
• complication,
• list,
• layer,
• usage,
• contamination,
• indication,
• surface,
• entertainment,
• area,
• specification,
• target,
• group,
• entity,
• comfort,
• transformation,
• development,
• injury,
• ingredient,
• illness,
• interaction,
• volatile,
• pathology,
• career,
• catastrophe,
• hazard,
• motion,
• fuel,
• form,
• process,
• solution,
• assistant,
• incident,
• agent,
• occurrence,
• failure,
• error,
• sector,
• information,
• inflammation,
• equipment,
• allergen,
• market,
• procedure,
• syndrome,
• state,
• system,
• disaster,
• emotion,
• malady,
• acid,
• protease,
• prey,
• danger,
• germ,
• request,
• residue,
• conflict,
• metal,
• precipitant,
• fluid,
• morbidity,
• mechanism,
• substance,
• pathogen,
• sport,
• antigen,
• difficulty,
• animal,
• facility,
• modification,
• chemical,
• pollutant,
• intermediate,
• lesion,
• predator,
• sentence,
• extra,
• means,
• problem,
• eruption,
• impurity,
• parasite,
• place,
• poison,
• virus,
• substrate,
• disturbance,
• change,
• opposition,
• precursor,
• thing,
• accident,
• abrasive,
• use,
• rodent,
• event,
• bacteria,