overhead projector
US /ˈoʊvərˌhɛd prəˈdʒɛktər/
UK /ˈoʊvərˌhɛd prəˈdʒɛktər/
1.
a device that projects an enlarged image of a transparency onto a screen or wall
:
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The teacher used an overhead projector to display the lesson notes.
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Before PowerPoint, presentations were often made with an overhead projector.