SEALANT

sealant, sealer

(noun) a kind of sealing material that is used to form a hard coating on a porous surface (as a coat of paint or varnish used to size a surface)

Source: WordNet® 3.1

Etymology

Noun

sealant (countable and uncountable, plural sealants)

Any material used to seal a surface so as to prevent passage of a fluid.

(construction) A mixture of polymers, fillers, and pigments used to fill and seal joints where moderate movement is expected.

Source: Wiktionary