nonchalant
/ˌnän-shə-ˈlänt/
adjective
having an air of easy unconcern or indifference
cool composed collected unruffled imperturbable nonchalant mean free from agitation or excitement. cool may imply calmness, deliberateness, or dispassionateness. composed implies freedom from agitation as a result of self-discipline or a sedate disposition.