noun (n)

• a warning against certain acts(noun.communication)

  Example:
  A caveat against unfair practices.
  

  Synonym:
  caution
  

  source: wordnet30
• (law) a formal notice filed with a court or officer to suspend a proceeding until filer is given a hearing(noun.communication)

  Example:
  A caveat filed against the probate of a will.
  

  source: wordnet30
• A notice given by an interested party to some officer not to do a certain act until the party is heard in opposition; as, a caveat entered in a probate court to stop the proving of a will or the taking out of letters of administration, etc.(noun)

  source: webster1913