self-possessed

Adjective

• in full control of your faculties
  • the witness remained collected throughout the cross-examination
    
  • perfectly poised and sure of himself
    
  • more self-contained and more dependable than many of the early frontiersmen
    
  • strong and self-possessed in the face of trouble
    

Related words

• Synonyms: 
  collected , equanimous , poised , self-collected , self-contained