What is the difference between caulk and caulking?

The difference between the words "caulk" and "caulking" is primarily grammatical, distinguishing between the material itself and the action or finished result of its application. "Caulk" functions primarily as a noun describing the physical, paste-like elastomeric substance or compound squeezed from a tube to fill gaps, as well as a verb denoting the act of applying that substance. In contrast, "caulking" typically functions as a participle, gerund, or collective noun referring to the continuous process of installing the sealant, the trade skill involved, or the final cured bead of material visible along a joint. While both terms are frequently used interchangeably in casual conversation among DIYers and contractors, understanding their subtle grammatical distinctions helps clarify whether you are discussing the product purchased at the hardware store or the labor-intensive technique of sealing gaps.