Source : WordNet®

HDL
     n : a lipoprotein that transports cholesterol in the blood;
         composed of a high proportion of protein and relatively
         little cholesterol; high levels are thought to be
         associated with decreased risk of coronary heart disease
         and atherosclerosis [syn: {high-density lipoprotein}, {alpha-lipoprotein}]

Source : Free On-Line Dictionary of Computing

HDL
     
        {Hardware Description Language}