1. the quality or state of being ungrateful; lack of appreciation or gratitude
2. the quality of receiving no thanks or recognition; being unappreciated

Examples

• The thanklessness of his children hurt him deeply after all he had done for them.
• She was shocked by the thanklessness shown by the community after her years of volunteer work.
• Teaching can be a job of thanklessness, with little recognition from students or parents.
• His thanklessness toward his mentor was evident in his refusal to acknowledge her help.
• The thanklessness of the task didn’t deter her from continuing her charitable efforts.
• Despite the thanklessness of caring for elderly patients, the nurse found the work rewarding.