Definition of "flashboard"
flashboard
noun
plural flashboards
(US) A board placed temporarily upon a dam, river, stream, etc. (typically within a permanent frame) to raise the water above its usual level.
Quotations
Although flashboards are designed to fail when reservoir level rises rapidly to an elevation greater than the flashboards, NPI states that most flashboard failures occur as a result of debris or ice hitting the flashboards.
1996, Sabina Joe, Final Environmental Impace statement: Wisconsin River Basin Hydroelectric Project, Vilas County, Forest County, pages 4-126
Any automated display that shows temporary information.
Quotations
Thus encroaching telephone wires, angrily projecting one's arm, an overhanging flashboard, or tree, leaning walls, and overhanging roof, projecting eaves and the shooting of guns have all been regarded as invasions of the superincumbent airspace — the exclusive realm of the landownder.
1957, The Journal of Air Law and Commerce - Volume 24, page 132
In jumping, a jump recording and display system was newly developed to meet the requirements of this fast-moving event in which the jumper's results were instantaneously displayed on the electronic flashboard after performing a complex score calculation.
1973, Dai 11-kai Orinpikku Tōki Taikai, Sapporo 1972, page 398
An electronic display that shows the winning values in various gambling games such as keno or bingo.
Quotations
The holder of a ticket that contains a match of all the numbers on any one of the Player's Cards to the numbers on the Flashboard card using the 48 Flashboard card numbers and the 49th and 50th Bonus Balls shall be entitled to a prize of $50.
1996, Florida Administrative Weekly - Volume 22, Issues 47-52, page 7028
In the middle of the table, a roll-down hopper connected to a flashboard. Players bought cards from the dealer, then tried to roll a ball into the hopper in such a way that the flashboard would register a card of a suit and number that would match the cards the players had bought, filling in a four-card sequence.
2003, Robert L. Shook, Jackpot!: Harrah's Winning Secrets for Customer Loyalty, page 9