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.
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
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.