From Longman Dictionary of Contemporary Englishthanklessthank‧less /ˈθæŋkləs/ adjective 1 DIFFICULTa thankless job is difficult and you do not get any praise for doing itthankless task/job/chore etc Cooking every day is a thankless task.2 literary a thankless person is not grateful
Examples from the Corpus
thankless• Dole stands up and shoulders the practical and often thankless burden of political leadership.• a thankless child• Shakur has charisma, and, luckily, the less thankless role: at least his character has a vestige of scruples.• In some ways that was a thankless task.• It seems an exhausting and thankless task.• Policing this activity to ensure submission of the reports is an unenviable and thankless task.• Do-gooding is often tough, thankless work.thankless task/job/chore etc• As every true Cornishman knows, it was the wicked Tregeagle who was supposedly punished with this thankless task.• In some ways that was a thankless task.• It seems an exhausting and thankless task.• Policing this activity to ensure submission of the reports is an unenviable and thankless task.• This president business is a pretty thankless job.• Looking for reasoning in the forex markets is a thankless task so we won't bother.Origin thankless (1500-1600) thank (noun); → THANKS2 