Agonizingness is a relatively uncommon word, and as such, synonyms for it may be difficult to come by. However, similar words may include suffering, torment, anguish, misery, and pain. These words all describe feelings of physical or emotional distress and can be used to convey the concept of agonizingness. Other possible synonyms might include excruciating, unbearable, gut-wrenching, and harrowing. Regardless of the specific word chosen, the overall meaning should be the same: an intense and agonizing experience that is difficult to endure. These words can all be used to describe moments of extreme pain, sadness, or hardship.