Antonyms of adj nail-biting
1 sense of nail-biting                                                  
Sense 1
cliff-hanging, suspenseful, suspensive, nail-biting -- ((of a situation) characterized by or causing suspense)
INDIRECT (VIA tense) -> relaxed -- (without strain or anxiety; "gave the impression of being quite relaxed"; "a relaxed and informal discussion")
Similarity of adj nail-biting
1 sense of nail-biting                                                  
Sense 1
cliff-hanging, suspenseful, suspensive, nail-biting -- ((of a situation) characterized by or causing suspense)
       => tense (vs. relaxed) -- (in or of a state of physical or nervous tension)

