Modifiers matching thread:

• solid,
• heavy,
• rigid,
• durable,
• strong,
• heavier,
• rough,
• firm,
• thin,
• finished,
• flexible,
• suitable,
• textured,
• twisted,
• round,

Simple categories matching rigid:

• material,
• hitch,
• sector,
• protein,
• surface,
• alteration,
• lining,
• space,
• cover,
• cloth,
• structure,
• display,
• container,
• package,
• object,
• adhesive,
• monomer,
• appendage,
• textile,
• obstacle,
• component,
• finish,
• food,
• substrate,
• body,
• article,
• profile,
• plate,
• frame,
• solid,
• item,
• fastener,
• splint,
• shaft,
• shape,
• movement,
• member,
• strip,
• base,
• covering,
• molecule,
• feature,
• device,
• instrumentation,
• post,
• barrier,
• vehicle,
• matter,
• case,
• substance,
• pavement,
• piece,
• casing,
• wall,
• document,
• hanger,
• bottle,
• medium,
• matrix,
• unit,
• thermoplastic,
• tube,
• portion,
• instrument,
• devices,
• rock,
• system,
• coil,
• cement,
• transformation,
• gel,
• implement,
• product,
• tissue,
• dressing,
• pipe,
• ground,
• construction,
• means,
• fabric,
• armour,
• plant,
• element,
• appliance,
• deck,
• boot,
• block,
• fixing,
• packing,
• mineral,
• boundary,
• rod,
• floor,
• support,
• deposit,
• stick,
• organ,
• airfoil,
• watercraft,
• web,
• connector,
• organs,
• foundation,
• sheet,
• metal,
• tip,
• plastic,
• sorbent,
• aggregate,
• layer,
• transparency,
• bed,
• fixture,
• polymer,
• connection,
• resin,
• entity,
• change,
• fiber,
• panel,
• motion,
• obstruction,
• paper,
• foam,
• mechanism,
• form,
• cylinder,
• part,
• carrier,
• tool,
• representation,
• filler,
• group,
• tubing,
• particle,
• fibre,
• macromolecule,
• luggage,
• architecture,
• insulation,
• measure,
• sphere,
• thread,
• class,
• cutoff,