Source : WordNet®

impact printer
     n : a printer that prints by mechanical impacts

Source : Free On-Line Dictionary of Computing

impact printer
     
         The earlier, noisier kind of {printer} where part of
        the mechanism comes into contact with the paper.  The term
        would only be only used in contrast to "{non-impact printer}".
        Examples include {line printer}, {daisy wheel printer}, {golf
        ball printer}, {dot matrix printer}, {Braille printer}.
     
        (1998-10-13)