out ‧ sid ‧ er /aʊtˈsaɪdə $ -ər/ BrE AmE noun [countable]
1 . someone who is not accepted as a member of a particular social group ⇨ insider :
I’m an outsider, the only foreign woman in the group.
to an outsider
To an outsider, the system seems complex and confusing.
2 . someone who does not belong to a particular company or organization or who is not involved in a particular activity ⇨ insider :
a political outsider who is running for governor
3 . someone who does not seem to have much chance of winning a race or competition
rank outsider British English :
Last year he was a rank outsider for the title.