Anxious or tense. The young man beside me, on thorns due to the train's delay, got up and began pacing back and forth down the length of the cabin. The situation left me on thorns: should I follow Molly, or stay and wait for help?
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
on thornscontinuously uneasy, especially in fear of being detected.
Farlex Partner Idioms Dictionary © Farlex 2017