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.
Anime loving people, in Japan, often collectivate in Harajuku Park on Sundays.