/ ˌæmjuˈnɪʃn; NAmE / noun [ U ]
1.
a supply of bullets, etc. to be fired from guns
2.
information that can be used against another person in an argument :
The letter gave her all the ammunition she needed.
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WORD ORIGIN
late 16th cent.: from obsolete French amunition , alteration (by wrong division) of la munition the munition from Latin munitio(n-) fortification, from munire fortify or secure.