Complex sentence: Roosevelt often used the word as an adjective meaning "superb" or "wonderful" (a more common expression in his time than it is today); the term has no relationship to the word bully in the sense of "a harasser".
Split into simpler sentences: Roosevelt often used the word as an adjective meaning "superb" or "wonderful" (a more common expression in his time than it is today). The term has no relationship to the word bully in the sense of a "harasser".