Modifiers matching world:

• real,
• solid,
• airless,
• unique,
• natural,
• mundane,
• new,
• over,
• smaller,
• allegorical,
• outer,
• interesting,
• virtual,
• physical,
• competitive,
• external,
• small,
• underwater,
• inner,
• visible,
• subatomic,
• large,
• remote,
• abstract,
• lifeless,
• waterless,
• everyday,
• agricultural,
• differentiated,
• visual,
• huge,
• biological,
• outside,
• inanimate,
• underground,
• vital,
• substantial,
• nonliving,
• distant,
• corporate,
• western,
• dense,
• modern,
• rocky,
• isolated,
• microscopic,
• advanced,
• nonprofit,
• botanical,
• public,
• developing,

Simple categories matching underground:

• area,
• bunker,
• structure,
• treasure,
• fortification,
• improvement,
• music,
• vegetable,
• group,
• duct,
• stem,
• installation,
• pest,
• facility,
• activity,
• storage,
• room,
• shelter,
• passage,
• object,
• organ,
• part,
• excavation,
• conduit,
• harvester,
• container,
• material,
• system,
• aquifer,
• service,
• location,
• supply,
• resource,
• formation,
• reservoir,
• pipeline,
• tank,
• works,
• world,
• enclosure,
• topic,
• void,
• cistern,
• opening,
• housing,
• fixture,
• hydrocarbon,
• tunnel,
• obstacle,
• cave,
• utility,
• equipment,
• feature,
• conductor,
• cavity,
• construction,
• plant,
• building,
• relic,
• fluid,
• band,
• wealth,
• pipe,
• property,
• line,
• development,
• space,
• expanse,
• liquid,
• work,
• obstruction,
• cable,
• cavern,
• life,
• item,
• place,