"Caulk"

"Caulking is a process used to seal the seams in wooden boats, in order to make them watertight. Caulking as a term has spread to the building trade, meaning the activity of closing up joints and gaps in buildings. This is mostly done with ready-mixed construction chemicals sold as caulk such as silicone, polyurethane, polysulfide, sylil-terminated-polyether or polyurethane and acrylic sealant. Unlike construction caulk, which is applied where no building movement is expected, a sealant is made of elastomeric materials that typically allow movement of 25% to 50% of the width of the joint. Silicone sealants form a durable, water-tight seal, but are not paintable."

I've been fixing some plumbing. Guess what I had to use...