lethargic

adjective
Definition of lethargic:

deficient in alertness or activity


Synonyms of lethargic:

unenergetic, sluggish, listless, lazy, inactive, torpid, slow, sleepy, slothful, apathetic


Opposite/Antonyms of lethargic:

energetic, active, busy, lively, perky, alert, vivacious, vigorous, vital, animated


Sentence/Example of lethargic:

If the cat is lethargic and his coat is dull and unhealthy looking, this too may be a sign.