lethargic \luh-THAHR-jik or leh-THAHR-jik\

(adjective)
1 : of, relating to, or characterized by drowsiness or sluggishness
2 : indifferent, apathetic

a. 기면(嗜眠)성[증]의; 혼수(상태)의; 무기력한, 활발하지 못한; 둔감한

Example sentence:
Louise called the vet when her cat became lethargic and stopped eating.