What term did Immanuel Kant use in 1755 for hypothesized separate, massive stellar systems resembling the Milky Way?

Answer

Island universes

Immanuel Kant extended the structural idea by suggesting that the fuzzy patches of light observed in the sky, then called nebulae, might actually be separate, massive systems composed of stars, which he termed 'island universes.'

What term did Immanuel Kant use in 1755 for hypothesized separate, massive stellar systems resembling the Milky Way?
astronomytheorystarMilky Way