Dictionary.net

• A kind of movable dam, in one form consisting of two leaves resting against each other at the top when raised and folding down one over the other when lowered, for deepening shallow parts in a river.

2010 - New Age Dictionary Database
By Oddity Software

• A kind of movable dam, in one form consisting of two leaves resting against each other at the top when raised and folding down one over the other when lowered, for deepening shallow parts in a river.

1913 - Webster's Revised Unabridged Dictionary
By Noah Webster.