root words: Collective & Migrate
collective - forming a whole; combined: the collective assets of a corporation and its subsidiaries.
migrate - to go from one country, region, or place to another.
collectivate = 1. formed by collection and migrating
2. a collective of things or person(s) that have gathered together.
The things in my room have collectivated together in the middle of the floor.
Anime loving people, in Japan, often collectivate in Harajuku Park on Sundays.