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sealant

SEE-luhnt /ˈsiː.lənt/

nounB2

technicalgeneral

A substance applied to a surface to make it impervious to water, air, or other fluids; a protective coating.

Sealant is a broad category that includes liquids, gels, and pastes designed to coat surfaces or fill joints to prevent leaks.

The story behind the word. Sealant is derived from the verb 'seal', which comes from the Latin 'sigillum', meaning a small sign, mark, or image. Historically, a seal was a wax impression used to close letters securely; modern sealants perform a similar protective closing function chemically.

Word relationships

seal: A seal can be a mechanical component (like an O-ring), whereas a sealant is always a chemical substance applied to a surface.
coating: A coating is any layer applied to a surface, whereas a sealant specifically aims to block the passage of fluids or air.

Commonly confused with

adhesive: An adhesive is designed primarily to bond two surfaces together structurally, while a sealant is designed to block water or air.

Word family

seal (verb): to close securely or make airtight
sealed (adjective): closed or secured with a seal

Collocations

waterproof sealant
silicone sealant
apply sealant
protective sealant

Example sentences

"Applying a high-quality water-resistant sealant to your wooden deck will protect it from rotting during the winter." Deck maintenance
"The mechanic applied a silicone sealant to the engine gasket to prevent oil from leaking out." Automotive repair

Memory hook

Think of a 'seal' (the animal) sliding smoothly through the water because its fur is coated in a waterproof 'sealant'. Sealant seals out water and air.

When not to use

Do not use sealant when referring to a mechanical fastener like a bolt or screw, though a sealant may be applied to their threads.

Fun facts

Many modern aerospace sealants are designed to withstand extreme temperatures ranging from -60°C to over 200°C without losing their flexibility.