Definition of supergalactic in English:
supergalactic
adjective ˌsjuːpəɡəˈlaktɪkˌsuːpəɡəˈlaktɪk
Astronomy Of or relating to a supergalaxy; that is, or is on, a scale larger than that of a galaxy.
Origin
1930s. From super- + galactic, after supergalaxy.