Modifiers matching invalid:

• socially-unintelligent,
• crippled,
• gentle,
• brilliant,
• arrogant,
• scientific,
• socially-unaware,
• bumbling,
• innocent,
• socially-awkward,
• inspirational,
• stubborn,
• aloof,
• sympathetic,
• weak,
• kind-hearted,
• inspiring,
• insightful,
• rigid,
• gangly,
• optimistic,
• good-hearted,

Simple categories matching stubborn:

• residue,
• hero,
• sidekick,
• person,
• dirt,
• policeman,
• contaminant,
• robot,
• warrior,
• detective,
• animal,
• deposit,
• daughter,
• disease,
• hunter,
• item,
• coating,
• condition,
• imperfection,
• lover,
• soil,
• soldier,
• lady,
• vampire,
• scientist,
• impurity,
• infection,
• discoloration,
• child,
• substance,
• athlete,
• cop,
• stain,
• actor,
• womanizer,
• pioneer,
• material,
• invalid,