self-possessed [ self-puh-zest, self- ]
1. having or showing control of one's feelings, behavior, etc.; composed; poised.
self-pos·sess·ed·ly [self-puh-zes-id-lee, -zest-lee, self-] /ˈsɛlf pəˈzɛs ɪd li, -ˈzɛst li, ˌsɛlf-/, adverb
collected, composed, confident, cool, easy, reserved, sedate, tranquil, unruffled, poised
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calm, collected, serene, cool, sedate.
Origin: First recorded in 1830–40
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