disappointing
1. [ adjective ] not up to expectations
Synonyms: unsatisfying dissatisfactory
Examples:

"a disappointing performance from one who had seemed so promising"

Related terms: unsatisfactory
2. [ noun ] an act (or failure to act) that disappoints someone
Synonyms: disappointment dashing_hopes
Related terms: failure disappoint
Similar spelling:   disappointingly
  disappoint
  disappointment
  disappointed
  disappointedly