DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   marker
       n 1: some conspicuous object used to distinguish or mark
            something; "the buoys were markers for the channel"
       2: a distinguishing symbol; "the owner's mark was on all the
          sheep" [syn: marker, marking, mark]
       3: a writing implement for making a mark