Native speaker - I have the same gut instinct on the connotations. But, the term 'isolationism' refers to an intentionally policy of isolating oneself (a nation

Native speaker - I have the same gut instinct on the connotations. But, the term 'isolationism' refers to an intentionally policy of isolating oneself (a nation, presumably). Solitude is close too - but I think would mean complete separation from everyone, even like-minded people. Like Superman has his fortress of Solitude, and it's not filled with other Supermen. As far as I know.