Socialism

I would say it's a little more complicated than that. Imo imperialism has to entail more than just a colonialist money grab. If we don't acknowledge things like ethnic hierarchy and expansionism then there isn't really a good term to describe the expansions of countries like Germany or japan during and before ww2. The same goes for the empirical expansion of the past.

I especially don't think west Germany would be an example of colonialism or imperialism, but I think you could argue with some degrees of success that imperialism happened in places like Kazakhstan during Soviet rule.