Complex sentence: Civilian is believed to have been used to refer to non-combatants as early as 1829, though the term "non-combatant" now refers to people in general who are not taking part of hostilities rather than just civilians.
Split into simpler sentences: Civilian is believed to have been used to refer to non-combatants as early as 1829. The term "non-combatant" now refers to people in general who are not taking part of hostilities, rather than just civilians.