caulk 
/ˈkɑ:k/ verb
caulks; caulked; caulk·ing /ˈkɑ:k/ verb [+ obj] : to fill the cracks or holes in (something) with a substance that keeps out water
▪ He carefully caulked the area around the windows.
▪ He carefully caulked the area around the windows.
— caulk noun [noncount]
▪ He filled the cracks with caulk.
▪ He filled the cracks with caulk.
