ˈnail-ˌbitinglyadv. in a manner that causes or reflects great anxiety or tension.
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1958 N.Y. Times 28 Mar. 29/3 All of these dangerous adventures are severely, nail-bitingly tense.
1995 Time Out 6 Dec. 151/4 (advt.) Brennan Street has a cast with a perfectionist's touch and directs with a look-no-hands ease that slowly and nail-bitingly reels you in.