Source : WordNet®

dot matrix printer
     n : a printer that represents each character as a pattern of
         dots from a dot matrix [syn: {matrix printer}, {dot
         printer}]

Source : Free On-Line Dictionary of Computing

dot matrix printer
     
         A kind of printer with a vertical column
        of up to 48 small closely packed needles or "pins" each of
        which can be individually forced forward to press an ink
        ribbon against the paper.  The print head is repeatedly
        scanned across the page and different combinations of needles
        activated at each point.
     
        Dot matrix printers are noisy compared to {non-impact
        printer}s.
     
        [Other pin arrangements?]
     
        (1995-03-14)