[{"Bold_text": "adjective", "List Items": ["stiff or unyielding; not pliant or flexible; hard:a rigid strip of metal.Synonyms: inflexible , firm , unbending Antonyms: elastic", "firmly fixed or set.Synonyms: static , immovable", "inflexible, strict, or severe:a rigid disciplinarian; rigid rules of social behavior.Synonyms: unyielding , stern , austere Antonyms: lax", "exacting; thorough; rigorous:a rigid examination.Synonyms: demanding", "so as to meet precise standards; stringent:lenses ground to rigid specifications.Synonyms: demanding", "Mechanics.of, relating to, or noting a body in which the distance between any pair of points remains fixed under all forces; having infinite values for its shear modulus, bulk modulus, and Young's modulus.", "Aeronautics.(of an airship or dirigible) having a form maintained by a stiff, unyielding structure contained within the envelope.pertaining to a helicopter rotor that is held fixedly at its root.", "(of an airship or dirigible) having a form maintained by a stiff, unyielding structure contained within the envelope.", "pertaining to a helicopter rotor that is held fixedly at its root."]}]