flashboard 
noun
A board used for sending more water from a mill dam into a mill race.Collecting activities were seriously curtailed in the 1930s when two flashboards, or risers, were added to the top of the extant concrete dam.
- buckeen
- bucket
- bucket brigade
- bucketful
- bucket hat
- bucket list
- bucketload
- bucket seat
- bucket shop
- bucketwheel
- buckeye
- buckeye butterfly
- buckeye coupling
- Buckeye State
- buck fever
- buckhorn
- buckhound
- Buckingham Palace
- Buckinghamshire
- buckjump
- buckjumper
- buckjumping
- Buckland, William
- buckle
- buckle bunny