What does leakproof mean?
Leakproof is an adjective describing an object or fitting that will not allow its contents to escape. It is especially common in packaging, engineering, outdoor gear, electronics, and household products, where a closure, seam, gasket, or material must prevent liquid or gas from passing through. The word combines leak with the established English element proof, meaning “protected against” or “able to withstand,” as in waterproof and fireproof. Leakproof usually describes a deliberate design feature rather than an accidental condition, so it carries a practical, reassuring connotation: the product is intended to contain what is inside it. Like many product descriptions, however, the term is sometimes used loosely and should not be treated as a guarantee unless supported by a specified standard. As a verb, leakproof is less common but can mean to make something resistant to leaking. Overall, the word is useful because it states both an object's function and the expectation of containment.
Incapable of leaking; designed to prevent liquid or gas from escaping.
"We packed the soup in a leakproof container for the journey."
To make something resistant to leaking.
"The engineers leakproofed the housing before subjecting it to pressure."
It puts a reassuring “proof” after “leak”: the product is meant to pass the leak test.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does leakproof come from?
Leakproof is an English compound formed from the older words leak and proof. Leak descends from Old English, while proof entered Middle English from Old French and ultimately from Latin probare, “to test.” In compounds such as leakproof, waterproof, and fireproof, proof has the productive meaning “guarded against” or “able to withstand.”
Related word forms
How leakproof is actually used
The adjective is common in technical writing, packaging descriptions, consumer goods, and outdoor equipment. It is usually written as one word, although the hyphenated form “leak-proof” also occurs. The verb is less common and is more natural in technical contexts than in everyday speech.
Easily confused with leakproof
Waterproof specifically means resistant to the passage or penetration of water, whereas leakproof means designed to prevent its contents from escaping through any leak.