What do a.m. and p.m. stand for?


[pen-stok] /ˈpɛnˌstɒk/
a pipe conducting water from a head gate to a waterwheel.
a conduit for conveying water to a power plant.
a sluicelike contrivance used to control the flow of water.
Origin of penstock
1600-10; pen2 + stock Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for penstock
  • Gravity causes it to fall through the penstock inside the dam.
  • To generate hydroelectricity, water from a river or reservoir is directed into a large pipe called a penstock.
  • Check condition of interior coating and exterior coating of exposed portions of penstock.
  • The water pressure is funneled through a tunnel through the dam called a penstock.
  • Inspections of de-watered external structures and of the penstock confirmed the presence of quagga mussels.
  • The penstock has been drained and filled with concrete to remove the source of water believed to be the cause of the problem.
  • When power is needed, water is released from the reservoir through a large pipe called a penstock and into a turbine.
  • Water from the reservoir rushes through the penstock into the powerhouse.
British Dictionary definitions for penstock


a conduit that supplies water to a hydroelectric power plant
a channel bringing water from the head gates to a water wheel
a sluice for controlling water flow
Word Origin
C17: from pen² + stock
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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penstock in Science
  1. A sluice or gate used to control a flow of water.

  2. A pipe or conduit used to carry water to a water wheel or turbine.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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