[waw-ter-tahyt, wot-er-]
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  1. constructed or fitted so tightly as to be impervious to water: The ship had six watertight compartments.
  2. so devised or planned as to be impossible to defeat, evade, or nullify: a watertight contract; a watertight alibi.

Origin of watertight

Middle English word dating back to 1350–1400; see origin at water, tight
Related formswa·ter·tight·ness, nounnon·wa·ter·tight, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for watertight

Historical Examples of watertight

British Dictionary definitions for watertight


  1. not permitting the passage of water either in or outa watertight boat
  2. without loopholesa watertight argument
  3. kept separate from other subjects or influencesdifferent disciplines are often thought of in watertight compartments
Derived Formswatertightness, noun
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

Word Origin and History for watertight

late 14c., from water (n.1) + tight. Figurative use from 1640s.

Online Etymology Dictionary, © 2010 Douglas Harper