Unsound/ˌʌnˈsaʊnd/ Definition 1 of 3Pro Tip 1/3Physical Safety Use 'unsound' to describe things that could collapse or break, posing danger. Walking on the unsound ice is risky. Pro Tip 2/3Avoid for People 'Unsound' is rarely used for people unless discussing their plans or ideas. He has unsound plans for the business. Pro Tip 3/3Serious Concern Describing something as 'unsound' implies a serious issue, not just a small defect. They condemned the unsound structure after the earthquake.