open sandwich
US /ˈoʊ.pən ˈsæn.wɪdʒ/
UK /ˈoʊ.pən ˈsæn.wɪdʒ/

1.
a sandwich that has only one slice of bread, with the filling on top
:
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For lunch, she prepared a delicious open sandwich with smoked salmon and cream cheese.
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In Denmark, open sandwiches, known as smørrebrød, are a popular dish.