slog
     v 1: work doggedly or persistently; "She keeps plugging away at
          her dissertation" [syn: {plug away}, {peg away}, {keep
          one's nose to the grindstone}, {keep one's shoulder to
          the wheel}]
     2: walk heavily and firmly, as when weary, or through mud;
        "Mules plodded in a circle around a grindstone" [syn: {footslog},
         {plod}, {trudge}, {pad}, {tramp}]
     3: strike heavily, especially with the fist or a bat; "He
        slugged me so hard that I passed out" [syn: {slug}, {swig}]
     [also: {slogging}, {slogged}]
Source: WordNet® 2.0