noun A board placed temporarily upon a dam, river, stream, etc. (typically within a permanent frame) to raise the water above its usual level.
noun A board that controls the flow of any material.
noun A sheet of material that is subjected to an electric pulse or flashover in order to produce plasma.
noun Any automated display that shows temporary information. An electronic display that shows the winning values in various gambling games such as keno or bingo.
noun An electronic display that shows the winning values in various gambling games such as keno or bingo.
noun An acrylic board used to display children's work in a school.
noun A board for displaying language material in the classroom, used like a flashcard but potentially holding more information.
noun A device used in the 1920s for teaching typing skills which provided feedback on which key was pressed by lighting up the corresponding value.