thankless   (TTS Sound)

The thankless has 2 Senses.

• thankless, unthankful, ungrateful
• 恩知らず
• not feeling or showing gratitude; "ungrateful heirs"; "How sharper than a serpent's tooth it is / To have a thankless child!"- Shakespeare
• 謝意を感じない、または示さないさま

• thankless, ungratifying, unappreciated
• not likely to be rewarded; "grading papers is a thankless task"
• たぶん報いられない