1. an imaginary line or one drawn on a map connecting all points of equal depth below the surface of a body of water.
  2. a similar line for indicating the depth below the surface of the earth of an aquifer or the top of the water table.

Origin of isobath

First recorded in 1885–90, isobath is from the Greek word isobathḗs of equal depth. See iso-, batho- Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for isobath


  1. a line on a map connecting points of equal underwater depth
Derived Formsisobathic, adjective

Word Origin for isobath

C19: from Greek isobathēs of equal depth, from iso- + bathos depth
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