Gigascorpions are desert dwelling monsters with vicious pincers. They are mentioned in the same breath as scarletias, frighteners, wights, lamias and crab spiders on one occasion and compared to dracolizards and griffins on another. The term is used interchangeably with the phrase "giant scorpion".
"I looked for the words "Witcher urgently needed". And then there'd be a sacred site, a dungeon, necropolis or ruins, forest ravine or grotto hidden in the mountains, full of bones and stinking carcasses. Some creatures which lived to kill, out of hunger, for pleasure, or invoked by some sick will. A manticore, wyvern, fogler, aeschna, ilyocoris, chimera, leshy, vampire, ghoul, graveir, were-wolf, giant scorpion, striga, black annis, kikimora, vypper... so many I've killed."
- - pg. 116 (UK) and 148 (US), The Last Wish (UK and US edition)