1Stiff, cold, or unfriendly (atmosphere or manner); edgy and tense.
会議室はギスギスした雰囲気だった。
The conference room had a tense, unfriendly atmosphere.
彼女の態度がギスギスしていて話しかけにくい。
Her attitude is cold and edgy, so it's hard to talk to her.
長時間の争論で部署の空気がギスギスしてきた。
After a long argument the department's atmosphere became tense.
2Thin and bony; scrawny—appearing emaciated or gaunt.
病気のせいで彼はギスギスした体つきになった。
Because of illness he became thin and gaunt.
あの犬は餌が足りず、ギスギスしている。
That dog is scrawny from lack of food.