Modifiers matching antigen:

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

Simple categories matching indoor:

• toy,
• sport,
• gathering,
• activity,
• wall,
• course,
• loudspeaker,
• facility,
• game,
• item,
• exercise,
• area,
• place,
• creature,
• renovation,
• performance,
• insect,
• material,
• recreation,
• furnishing,
• support,
• space,
• vehicle,
• control,
• event,
• location,
• object,
• pest,
• task,
• institution,
• surface,
• light,
• pollutant,
• appliance,
• project,
• establishment,
• arena,
• problem,
• fun,
• allergen,
• passage,
• thing,
• plant,
• graphics,
• art,
• usage,
• equipment,
• celebration,
• housing,
• use,
• devices,
• coating,
• pool,
• venue,
• restaurant,
• partition,
• climate,
• food,
• obstruction,
• application,
• shot,
• decoration,
• stadium,
• room,
• exhibit,
• particle,
• contaminant,
• antigen,
• source,
• noise,
• tile,
• bird,
• fitting,
• structure,
• meeting,
• entertainment,
• air,
• ornament,
• diversion,
• fixture,
• unit,
• photograph,
• theatre,
• housework,
• flower,
• machine,
• quality,
• environment,
• communication,
• lodging,
• device,
• building,
• antenna,
• container,
• organism,
• chemical,
• substance,
• dog,
• substrate,
• site,
• houseplant,
• scene,
• treatment,
• athletics,
• shelter,
• product,
• fountain,
• set,
• job,
• centre,
• floor,
• component,
• pesticide,
• installation,
• clientele,
• covering,
• attraction,
• particulate,
• action,
• pet,
• party,
• medium,
• allergy,
• play,
• sound,
• gas,
• firework,
• lighting,
• atmosphere,
• function,
• furniture,
• work,
• lamp,
• fuel,
• exposure,
• assembly,
• stuff,
• condition,
• display,
• setting,
• animal,
• enclosure,
• drain,