waterproof

From water +‎ -proof. Compare West Frisian wetterproef (“waterproof”), Dutch waterproef (“waterproof”).

• (Received Pronunciation) IPA^(key): /ˈwɔːtəˌpruːf/

• Audio (Southern England):

  (file)

• (General American) IPA^(key): /ˈwɔt̬ɚˌpruf/, /ˈwɑ(ː)t̬ɚ-/

waterproof (comparative more waterproof, superlative most waterproof)

1. Resistant to the effects of water.
2. Made of or covered with material that doesn't allow water in.
   • 2025 October 21, Rose George, “‘I knew in my head we were dying’: the last voyage of the Scandies Rose”, in The Guardian‎^[1]:

     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.

3. (figurative) Incapable of failing; unassailable.
   • 1931, The British Clay Worker:

     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.

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

     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.

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

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

• (made of a material that doesn't allow water in): waterfast, watertight

• → French: waterproof
• → Italian: waterproof
• → Romanian: waterproof
• → Russian: ватерпру́ф (vaterprúf)

waterproof (third-person singular simple present waterproofs, present participle waterproofing, simple past and past participle waterproofed)

1. To make waterproof or water-resistant.
   • 2013 August 3, “Yesterday’s fuel”, in The Economist, volume 408, number 8847:

     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).

waterproof (plural waterproofs)

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

waterproof (feminine waterproofe, masculine plural waterproofs, feminine plural waterproofes)

1. (anglicism) waterproof

• “waterproof”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012

Unadapted borrowing from English waterproof.

waterproof (invariable)

1. waterproof (all senses)

   Synonym: impermeabile

Borrowed from English waterproof.

waterproof n (plural waterproofuri)

1. a waterproof cloak