caulk
Caulk (noun) means a flexible waterproof filler squeezed into joints and gaps — around baths, sinks, window frames and skirting boards — to seal them against water and draughts. Example: “Run a bead of caulk along the edge where the bath meets the tiles.”
How to use caulk
Learner’s notesIn plain EnglishSquishy waterproof filler you squeeze into gaps so water cannot get through.
Neutral. Everyday in DIY and trade contexts; the noun is more common in American English than British, where sealant dominates.
Caulk fills the flexible joint where two different surfaces meet; grout fills the rigid gaps between tiles. Using grout where caulk belongs causes cracking.
Trace the full origin ↓Fill the gap
Can you complete this real example?
Run a bead of _____ along the edge where the bath meets the tiles.
Etymology
From Old North French cauquer, from Latin calcare 'to tread or press down', reflecting the original sense of pressing material into a ship's seams.
Synonyms
View more →Related words
Frequently asked questions
What is the difference between caulk and silicone?
Silicone is one type of caulk, not a rival product. Caulk is the general word for a gap-filling sealant; silicone caulk stays flexible and waterproof so it suits baths and showers, while acrylic or latex caulk can be painted over and suits skirting boards and trim.
Is caulk spelled differently in Britain?
Both caulk and calk appear historically, but caulk is now standard everywhere. In British usage the product is just as often called sealant or mastic, and the tube is bought as bathroom sealant rather than caulk.
How is caulk pronounced?
It rhymes with talk and walk — the L is silent. Saying it as kalk is a common misreading.
What is the meaning of caulk?
"caulk" (noun) means a flexible waterproof filler squeezed into joints and gaps — around baths, sinks, window frames and skirting boards — to seal them against water and draughts.