1. To remove something with blows from a sharp instrument: The lumberjack hacked away the larger limbs from the tree before felling it. The gardener used a large pair of shears to hack the dead twigs away.
2. hack away at To reduce or attempt to reduce something in size by chopping off pieces of it: The butcher hacked away at the side of beef to remove the fat.
3. hack away at To reduce something gradually by working at it continuously: I'm hacking away at the pile of reports on my desk.