simple past tense and past participle of disappoint
"After waiting all day, she was disappointed when the concert was cancelled."
In plain English: To disappoint means to let someone down by not meeting their expectations.
"The teacher disappointed her students by canceling the field trip last minute."
disappointingly unsuccessful
"disappointed expectations and thwarted ambitions"
"their foiled attempt to capture Calais"
"many frustrated poets end as pipe-smoking teachers"
"his best efforts were thwarted"
Defeated of expectations or hope; experiencing disappointment; let down.
"Sarah was disappointed when her team lost the championship game, leaving everyone feeling let down after weeks of hopeful anticipation."
In plain English: Feeling let down because something did not happen as you expected it to.
"She was disappointed to find the restaurant closed on Sundays."
Usage: Use disappointed to describe someone who feels sad because an outcome was worse than expected, rather than using it as the noun form which is incorrect in standard English. This adjective typically modifies a person's emotional state after a specific event fails to meet hopes or desires.