thankless

Adjective

• not likely to be rewarded
  • grading papers is a thankless task
    

• not feeling or showing gratitude
  • ungrateful heirs
    
  • How sharper than a serpent's tooth it is / To have a thankless child!- Shakespeare
    

Related words

• Synonyms: 
  unappreciated , ungratifying , ungrateful , unthankful
• Antonyms: 
  grateful , thankful