rat·line
also rat·lin (răt′lĭn)n.1. Any of the small ropes fastened horizontally to the shrouds of a ship and forming a ladder for going aloft.
2. The material used for these ropes.
[Alteration (perhaps influenced by rat, with reference to ships' rats) of Middle English ratheling in ratheling line, thin cordage used for ratlines, from Middle English rathelen, to entwine + probably from alteration of Middle English raddle, stick, wattle, hurdle woven from wattle, perhaps from Anglo-Norman ridele, redele, rail on the side of a cart, probably of Germanic origin and akin to Middle High German reitel, reidel, toggle, turning handle, Old High German rīdan, to turn, wind; and Old English wrīthan, to writhe; see writhe.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
ratline
(ˈrætlɪn) or ratlin
n (Nautical Terms) nautical any of a series of light lines tied across the shrouds of a sailing vessel for climbing aloft
[C15: of unknown origin]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
rat•line
or rat•lin
(ˈræt lɪn)
n. any of the small ropes or lines that cross the shrouds of a ship horizontally and serve as steps for going aloft.
[1475–85; earlier ratling, radelyng, of obscure orig.]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ratline
An organized effort for moving personnel and/or material by clandestine means across a denied area or border.
Dictionary of Military and Associated Terms. US Department of Defense 2005.