these are various meanings of phlegmatic a. Having or suggesting a calm, sluggish temperament; unemotional or apathetic. b. not easily excited to action or display of emotion; having a calm or apathetic temperament.. synonymes apathetic, stoic, cold-blooded, sluggish. Antonymes edgy, excitable. LIVELY is therefore the opposite of phlegmatic from the options given above. it means to be; a. Full of energy or alertness; vigorous or animated: a lively baby; lively eyes. b. Characterized by much activity or excitement: