with all marbles (adjective) levelheaded: reasonable, calm
Sinonime: all there,
balanced,
collected, commonsensical,
composed,
cool, cool as cucumber, coolheaded,
dependable,
discreet, even-tempered, far-sighted, in one's right mind,
judicious,
practical,
prudent,
rational,
sane, self-possessed,
sensible,
steady,
together, unflappable,
wise, with all marbles
Antonime: nervous,
unreasonable,
upset