Why is the ninth month called September?
late 14c., "to stop up crevices or cracks," from Old North French cauquer, from Late Latin calicare "to stop up chinks with lime," from Latin calx (2) "lime, limestone" (see chalk). Original sense is nautical, of making ships watertight. Related: Caulked; caulking. As a noun, "caulking material," by 1980 (caulking in this sense was used from 1743). Related: Caulker.