appalling · adjective /əˈpɔː.lɪŋ/
appalling
C2 awful, or shocking and very unpleasant or causing someone to feel upset
Dictionary examples:
The animals were being kept in appalling conditions.
This industry has an appalling environmental record.
Both candidates showed an appalling lack of familiarity with the issues.
Learner example:
When Susan got the news of his illness all her joy turned into an appalling despair, and she felt she would die too. (Certificate of Proficiency in English; C2; Spanish)