The word "heart-sickening" describes something that is deeply disturbing, distressing or discomforting. Some synonyms for this phrase include "gut-wrenching", "agonizing", "soul-crushing" and "devastating". Each of these words evoke a strong emotional response and convey the intense feeling of despair or sadness associated with the phrase "heart-sickening". Other synonyms include "heartbreaking", "harrowing", "traumatic" and "excruciating". No matter which synonym is used, the meaning remains the same, and each word reflects the depth of pain and sadness that comes along with the experience of something that is truly heart-sickening.