Simple categories matching hollow:

• tubing,
• article,
• cylinder,
• object,
• jewelry,
• structure,
• tree,
• wall,
• area,
• part,
• shaft,
• conduit,
• item,
• ware,
• polyhedron,
• pole,
• bones,
• passage,
• ball,
• assembly,
• organ,
• dish,
• glass,
• thing,
• container,
• shape,
• vessel,
• reed,
• handgrip,
• surface,
• panel,
• piece,
• viscera,
• form,
• protuberance,
• carrier,
• section,
• material,
• sphere,
• stem,
• wood,
• bird,
• space,
• ceiling,
• viscus,
• product,
• beads,
• particle,
• cavity,
• shell,
• animal,
• bone,
• utensil,
• construction,
• needle,
• receptacle,
• organs,
• tissue,
• plant,
• component,
• tube,
• feature,
• fibre,
• implement,
• formation,
• fiber,
• pipe,
• glassware,
• region,
• instrument,
• body,

Members with property hollow:

• teat_cup,
• pocket,
• bottle,
• vagina,
• cup,
• aperture,
• bark_box,
• ceiling_panel,
• lung,
• tube,
• bowls,
• pipe,
• human_organs,
• urethra,
• ear,
• tubular_structure,
• lotion_bowl,
• earring,
• suspended_ceiling,
• storage,
• tubular_film,
• animal_horn,
• biopsy_needle,
• mold,
• room_partition,
• door_handle,
• foundry_core,
• stomach,
• tank,
• pneumothorax,
• sugar,
• door,
• silica_sphere,
• heart,
• container,
• sinus,
• rectangle,
• aircraft_wings,
• coil,
• canister,
• nuclear_reactor,
• cargo,
• airway,
• chimney,
• seaplane_body,
• hood,
• drum,
• cone,
• ureter,
• flask,
• section,
• glove,
• beads,
• rectangular_form,
• stove,
• arbor_leg,
• ballpoint_pen,
• kettle,
• large_intestine,
• shelter,
• boat_hull,
• hat,
• fiber,
• cooking_vessel,
• beech,
• wall,
• renal_pelvis,
• cannular_needle,
• digestive_organs,
• small_vase,
• cam_body,
• boat,
• small_bowel,
• automobile_stabilizer,
• sphere,
• structure,
• small_shelter,
• rounded_box,
• glass_beads,
• lymphatic_vessel,
• circle,
• urinary_bladder,
• small_bottle,
• conveyor_roller,
• support_post,
• stent,
• fuel_rack,
• appliance_part,
• ball,
• bamboo_cane,
• gut,
• pneumatic_cushion,
• hi_mouth,
• inside,
• liver,
• reed,
• cement_block,
• basswood,
• carton,
• envelope,
• cabinet,
• hypodermic_tubing,
• corporation,
• pipe_connector,
• dead_branch,
• bones,
• baobab,
• space_frame,
• leaching_gallery,
• hollow_sphere,
• tubing,
• trapezoid,
• duodenum,
• sport_ball,
• aluminum_tubing,
• crevice,
• injection_needle,
• hole,
• concrete_manhole,
• case,
• small_intestine,
• sinus_cavity,
• balloon,
• milk_jug,
• teapot,
• bell,
• rack,
• pvc_pipe,
• esophagus,
• pitcher,
• spiral_tube,
• similar_article,
• porcupine,
• glass_jar,
• racquetball,
• cyst,
• pillow,
• femur,
• cheekbone,
• plasterboard,
• bubble,
• steel_tube,
• pvc,
• beaker,
• table-tennis_ball,
• glass,
• flexible_endoscope,
• table_ware,
• doll,
• shoes_boot,
• jacks,
• jug,
• fuel_tank,
• wood,
• crack,
• oil_tank,
• chicken_bones,
• bubble_wrap,
• spark-plug_shell,
• intestine,
• sycamore,
• box,
• doughnut,
• bushing,
• fence_post,
• gastrointestinal_tract,
• needle,
• engine_cradle,
• macaw,
• plastic_pallet,
• jumper,
• tibia,
• animal_shell,
• soda-pop_bottle,
• sheetrock,
• flute,
• neck,
• rectum,
• cooling_pipe,
• passage,
• mirror_head,
• cage,
• gas,
• playing_ball,
• food_canal,
• quill,
• gravid_uterus,
• candle_stick,
• spoon,
• tile,
• branch,
• peritoneal_cavity,
• belly,
• urinary_tract,
• pressure_vessel,
• truncated_cone,
• glass_block,
• trench,
• table_glass,
• bowel,
• football,
• ventilation_slot,
• hot-water_bottle,
• automotive_part,
• speaker,
• glass_container,
• cavity,
• brain,
• strut,
• injection_bottle,
• tissue_forceps,
• shampoo_bottle,
• fossil_shell,
• digestive_tract,
• valve,
• straw,
• casing,
• thermoplastic_hose,
• gastrointestinal_organs,
• funnel,
• trash_pit,
• duct,
• mask,
• hollow_cone,
• chicken,
• torso,
• lentil_cube,
• mast,
• golf-club_shaft,
• airplane_wings,
• vein,
• column_cover,
• rubber_glove,
• milk_bottle,
• trachea,
• metal_container,
• pan,
• kidney,
• pancreas,
• cushion,
• ceiling,
• solid_disk,
• cylindrical_form,
• goblet,
• lower_bowel,
• city,
• polygonal_shape,
• tool_holder,
• sexual_gratification,
• tunnel,
• gourd,
• toy,
• bin,
• frontal,
• piling,
• flagon,
• doughnut_shape,
• crucible,
• catwalk_framework,
• decorative_vessel,
• nose,
• gantry,
• playground,
• pig,
• adding_stone,
• bowl,
• coffeepot,
• plastic_tank,
• drum_beads,
• table_plate,
• ring,
• drain_pipe,
• panel,
• golf-club_head,
• storage_container,
• furniture_elements,
• horn,
• tankard,
• cylinder,
• roll,
• tray,
• jewelry_ring,
• wall_void,
• lid,
• saucer,
• steel_shell,
• parrot,
• plastic_straw,
• bronchial_tube,
• foam,
• hoop,
• shoes,
• pit,
• silo,
• human_urethra,
• doll_head,
• uterus,
• cotton_fibre,
• glasses,
• bicycle_component,
• gelatin_capsule,
• urogenital_tract,
• bladder,
• metal_cylinder,
• square,
• colon,
• roof,
• hollow_bowls,
• piano,
• windpipe,
• anaesthetic_bowls,
• stone_fragment,
• conduit,
• cartridge_case,
• bearing,
• oven,
• squeaky_toy,
• oval,
• helmet,
• tattoo_tube,
• side_board,
• concave_plate,
• rubbish_bin,
• cartridge_shell,
• light_pole,
• basketball,
• oxygen_tank,
• crockery,
• reactor,
• jar,
• milk_tube,
• middle-ear_anatomy,
• shell,
• ear_piece,
• crankshaft_bushing,
• storage_box,
• cotton,
• dome,
• gallbladder,
• attic_space,
• enclosure,
• gimbal,
• automobile_body,
• carbon_sphere,
• capsule,
• building,
• stein,
• fiberglass,
• bodywork,
• gypsum_wallboard,
• masonry_chimney,
• cystic_duct,
• vessel,
• plastic_bottle,
• circular_tube,
• plaster,
• brick,
• alveolus,
• aircraft-engine_component,
• softball,
• play_ball,
• box_section,
• glomerulus,
• catheter,
• sponge,
• leather,
• appendix,
• eye,
• cheek,
• triangle,
• under_eyes,
• bamboo,
• table_legs,
• plasterboard_wall,
• wings,
• bronchus,
• mullion,
• artery,
• vase,
• missile_casing,
• sea_shell,
• synthetic-resin_bottle,
• hollow_body,
• tubular_component,
• acrylonitrile_sphere,
• partition,
• tiled_wallboard,
• plate,
• syringe_needle,
• furnace_tube,
• coffee_pot,
• door_frame,
• concrete_pole,
• automotive_component,
• pore_size,
• dish,
• barrels,
• bracelet,
• ash,
• mug,
• closed_building,
• bag,
• abdomen,
• wallboard,
• joint,
• pump,
• chassis_part,
• large_auditorium,
• pillar,
• hose,
• organs,
• conical_shell,
• owl,
• dummy,
• drywall,
• insect_skeleton,
• frame,
• tub,
• head,
• hollow_door,
• polyelectrolyte_capsule,
• pore,
• metal_gutter,
• capillary,
• long_tube,
• bark,
• dog,
• oil_drum,
• aorta,
• deep_cup,
• side_sill,
• borosilicate_glass,
• pendant,
• center_pillar,
• hand_piece,
• gun_tube,
• kidney_dish,
• ewer,
• microtubule,
• can,
• academic_accolade,
• cube,
• pipe_stem,
• front_pillar,
• seminal_vesicle,
• radiator_frame,
• drain,
• pot,
• handle,
• brow,
• crate,