Appalling means shocking, horrifying or disgraceful. It is something that causes great horror, disgust or disappointment.
Usage examples
The condition of the abandoned building was appalling, with graffiti covering the walls and broken glass littering the floor.
The behavior of the unruly fans at the football match was absolutely appalling, as they threw objects onto the field and verbally abused the players.
The company's decision to dump toxic waste into the nearby river was truly appalling, showing a complete disregard for the environment and public health.
The level of poverty in some of the world's underdeveloped countries is truly appalling, with millions of people living without access to basic necessities such as clean water and food.
The teacher's treatment of the students was appalling, as she consistently belittled and humiliated them in front of their classmates.
Thousands of bears are being kept in appalling conditions to supply traditional Chinese medicine. (newscientist.com)
I have seen animals in more appalling conditions than I have ever seen any human in, and they still have trust for people and want to please and love. (todaysveterinarynurse.com)
... Worst of all, you possess the most appalling of all defects for a man in your position: You are fundamentally unjust. (familyllb.com)