Gollum on the edge of the abyss was fighting like a mad thing with an unseen foe.
But come, my friend, let us not speak of it! Let us not speak at all! I stand upon some dreadful brink, and it is utterly dark in the abyss before my feet, but whether there is any light behind me I cannot tell.
Out from the Dark Tower’s huge western gate it came over a deep abyss by a vast bridge of iron, and then passing into the plain it ran for a league between two smoking chasms, and so reached a long sloping causeway that led up on to the Mountain’s eastern side.
There are no more uses of "abyss" in the book.
Show samples from other sources
These were men who had built up wealth and social status over long careers and now found themselves looking into the abyss. [of the 1987 stock market crash]
Alan Greenspan -- The Age of Turbulence
The nerve-grinding squeal of the spike cutting through the ground sent a shiver up Thomas’s spine, though a second later the Griever tumbled into the abyss.