[{"Bold_text": "noun", "List Items": ["a person or thing that watches or stands as if watching:The cats were the sentinels of the house, patrolling constantly for rodents, dogs, and other invaders.Synonyms: lookout , watch , guard , sentry", "a soldier stationed as a guard to challenge all comers and prevent a surprise attack:Lincoln refused to make his home mansion a garrison during the Civil War, but plain-clothes sentinels did patrol the property Synonyms: lookout , watch , guard , sentry", "Digital Technology. tag1(def9a) tag1(def9a).", "Medicine/Medical.an indication or mark that a disease is present or prevalent:New viruses in the wastewater can be used as sentinels of future outbreaks."]}, {"Bold_text": "verb (used with object)", "List Items": ["to watch over or guard as a sentinel:This monument sentinels each soldier's grave as a shrine."]}, {"Bold_text": "adjective", "List Items": ["Medicine/Medical.relating to or being an indication of a disease's presence or prevalence:Pregnant women attending prenatal appointments serve as a sentinel population for the prevalence of malaria in the region.The sentinel lymph nodes are the first lymph nodes that the cancer cells reach if they spread."]}]