Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
self-possession is a noun meaning "the trait of resolutely controlling your own behavior". It carries one recorded sense.
the trait of resolutely controlling your own behavior
Definitions, synonyms and semantic relations for self-possession come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.