What is another word for rigid?

Another word for rigid is stiff, inflexible, unbending, unyielding, firm, hard, solid, inelastic, taut, strict, stringent, uncompromising, rigorous, and stern, depending on context. For physical objects, another word for rigid is stiff, as in stiff board that does not bend, or solid, firm, and hard. For rules, another word is strict, stringent, or inflexible, as in strict rules. For behavior or personality, another word is inflexible, stubborn, obstinate, unadaptable, and set in ways. For example, rigid schedule can be called fixed schedule or inflexible schedule. Rigid thinking can be called narrow-minded or unyielding thinking. So synonyms vary, but core synonyms are stiff for physical and inflexible for figurative, both capturing idea of not bending or changing. Thesaurus lists many synonyms, but most common are stiff and inflexible, which cover both physical and metaphorical uses of rigid.