overture
US /ˈoʊ.vɚ.tʃɚ/
UK /ˈoʊ.vɚ.tʃɚ/

1.
an orchestral piece at the beginning of an opera, oratorio, or other extended work.
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The opera began with a dramatic overture.
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The composer wrote a beautiful overture for the ballet.
2.
an introduction to something more substantial.
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His speech was an overture to a new policy.
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The peace talks were seen as an overture to a lasting agreement.
3.
an approach or proposal made to someone with the aim of opening negotiations or establishing a relationship.
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The company made an overture to their competitor for a merger.
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She rejected his romantic overtures.