Final answer:
The word 'belligerent' means a nation at war or a member of the military forces of a warring nation.
Step-by-step explanation:
The best definition for the word 'belligerent' is 'a nation at war; a member of the military forces of a warring nation'. It refers to a state of being hostile or aggressive, specifically in the context of war. For example, during World War II, Germany and Japan were belligerent nations.
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