waterproof

comparative more waterproof · superlative most waterproof

1. broadlybut commonResistant to the effects of water.

   Synonyms: water-resistant

2. strictlyMade of or covered with material that doesn't allow water in; impervious to water and immune to its effects.

   1 more example

   The captain did a safety drill. This covered where the emergency position-indicating radio beacon (EPIRB) was located, how to make a mayday call, and where the fire extinguishers were. A crew member demonstrated how to put on an immersion suit. These survival suits are waterproof full-body garments with a hood and integral three-finger gloves and boots. They are bulky and hard to get on but far more likely to save your life in cold water than a lifejacket.

   2025 October 21, Rose George, “‘I knew in my head we were dying’: the last voyage of the Scandies Rose”, in The Guardian

   Synonyms: waterfast, watertight

3. figurativelyIncapable of failing; unassailable.

   Unless you have a 100 percent waterproof plan to defraud insurance companies, I would suggest you don't do it.

   2013, Barry Davies, Soldier of Fortune Guide to How to Disappear and Never Be Found, Skyhorse Publishing, Inc., →ISBN

   2 more examples

   The only waterproof plan and the one increasingly adopted by leading trades is the consolidation of the interests of all parties in a scheme of amalgamation.

   1931, The British Clay Worker

   Especially within an international framework, guarding this process is of the utmost importance. The eyes of the world are focussed on the action at hand and demand a waterproof plan and execution.

   2001, W. A. M. van Dijk, J. L. Hovens, Netherlands. Koninklijke Marechaussee, Arresting war criminals

4. uncommonNot dependent on an aquatic environment to live; thus, able to live on dry land, or at least in a semiaquatic environment.

present singular third person waterproofs · participle present waterproofing · participle past waterproofed · past waterproofed

1. To make waterproof or water-resistant.

   The dawn of the oil age was fairly recent. Although the stuff was used to waterproof boats in the Middle East 6,000 years ago, extracting it in earnest began only in 1859 after an oil strike in Pennsylvania. The first barrels of crude fetched $18 (around $450 at today’s prices).

   2013 August 3, “Yesterday’s fuel”, in The Economist, volume 408, number 8847

plural waterproofs

1. countableuncountableA substance or preparation for rendering cloth, leather, etc., impervious to water.
2. countableuncountableCloth made waterproof, or any article made of such cloth, or of other waterproof material, as rubber; especially, an outer garment made of such material.

   Carrados dropped the near window as a man in glistening waterproof stepped from the shelter of a lich-gate and approached.

   1914, Ernest Bramah [pseudonym; Ernest Brammah Smith], Max Carrados