Complex sentence: The term "extremism" is usually meant to be pejorative: to express (strong) disapproval, but it may also be meant in a more academic, purely descriptive, non-condemning sense.
Split into simpler sentences: The term "extremism" is usually meant to be pejorative; that is, to express (strong) disapproval. However, it may also be meant in a more academic, purely descriptive, non-condemning sense.