An apparatus for depositing and consolidating concrete under water, essentially a tube of wood or sheet metal with a hooperlike top. It is usually handled by a crane.

device for placing concrete underwater; consists of a large metal tube with a hopper at the top end and a valve arrangement at the submerged end

(1) (verb)To place concrete below water level though a pile, the lower end of which is kept immersed in fresh concrete so that the rising concrete from the bottom displaces the water without washing out the cement content. (2) (noun) The hopper and drop pipe used to place the concrete underwater.