know what makes tick (verb) have someone's number: know someone's motives
Sinonime: acute,
agonizing,
burning, chastening,
consuming, exquisite,
extreme,
grueling,
harrowing, insufferable,
intense, piercing, punishing, racking, rending, searing, severe, sharp, shooting, stabbing, tearing, tormenting, torturesome, torturing,
unbearable, unendurable, violent
Antonime: bearable, endurable,
helpful,
pleasant,
pleasing,
soothing