is caulking

• present progressive

  present progressive

  Used to describe an ongoing action or state that is currently taking place in the immediate present.

  of caulk (3rd person singular).
  caulk

  verb (used with object)

  to fill or close seams or crevices of (a tank, window, etc.) in order to make watertight, airtight, etc.

Related Words

• block
• shut
• shutter