[{"Bold_text": "adjective", "List Items": ["characterized by rigor ;rigidly severe or harsh, as people, rules, or discipline:rigorous laws.Synonyms: unyielding , stiff , inflexible , hard , austere , stern Antonyms: soft , flexible", "severely exact or accurate; precise:rigorous research.Synonyms: finical , demanding Antonyms: inaccurate", "(of weather or climate) uncomfortably severe or harsh; extremely inclement.Synonyms: bitter , hard Antonyms: mild", "Logic, Mathematics.logically valid."]}]