self-possessed 
adjective
Calm, confident, and in control of one’s feelings; composed.She was very self-possessed and very confident....
- What I do envy, self-possessed control freak that I am, is other people's ability to lose themselves in unfettered delight.
- While emphasizing her innocence, the newspapers could not help noticing that ‘the little mite’ seemed self-possessed and confident, and much more mature than the older Clara.
Synonyms
assured, self-assured, calm, cool, {cool, calm, and collected}, composed, at ease, tranquil, serene, unperturbed, unruffled, impassive, nonchalant, confident, self-confident, sure of oneself, poised, dignified, equable, imperturbable, suave, urbane, elegant
informal together, unfazed, unflappable
rare equanimous
