Wiktionary
thock
interj. A clear, echoing thud, as of an axe chopping wood.
Usage examples of "thock".
Now he could hear bullets going by, or going thock into the hard mud-brick walls of the hospital building, or making a peculiar crunching shrush into the sacks of barley.
Tangleleaf and thrushtarn bushes grew thickly where the light fell, making hedges on either side of the trail, and they could hear the thock of axes on chopping blocks ahead, and the creaking of cartwheels.
But I had to make a few littleahrightings in the books, because otherwise one who didnt understand the conditions might have drawn the wrong thocks from them.