Synonyms for Levelheaded:

adj.

common-sense (adjective)
sound.
commonsensical (adjective)
commonsensible.
far-sighted (adjective)
sagacious, sage.
level-headed (adjective)
reasonable.
levelheaded (adjective)
judicious, commonsensical, balanced, rational, wise, sane, sensible, prudent.
rational (adjective)
intelligent.
sound (adjective)
well-founded.

n.

prudent, balanced, judicious, reason, commonsensible, sagacious, sane, rational, wise, well-founded, sage, sapient, commonsensical. levelheaded (noun)
intelligent, sensible, reasonable, sound, healthy.

Other synonyms:

commonsensible, commonsensical. judicious, well-founded. rational, balanced, prudent, sapient, sage, sane. sagacious. wise. Other relevant words:
prudent, balanced, judicious, reason, commonsensible, sagacious, sane, rational, wise, well-founded, sage, sapient, commonsensical.