hypernatremic UK /ˌhaɪ.pə.nəˈtɹiː.mɪk/US /ˌhaɪ.pɚ.nəˈtɹi.mɪk/ adjective1 •Having an abnormally high concentration of sodium (or salt) in blood plasma.Although nearly half the hypernatremic patients had a febrile illness, other associated conditions assume more prominence than in infants. — 1991 formsmore hypernatremic · most hypernatremic