Complex sentence: It is a word cognate with the English word with the same meaning as an adjective, but more importantly its homonym as a noun, "Reich", is usually used in German to designate a kingdom or an empire and also the Roman Empire.
Split into simpler sentences: It is a word cognate with the English word with the same meaning as an adjective. More importantly, its homonym as a noun, "Reich", is typically used in German to designate a kingdom or an empire, especially the Roman Empire.