thankless
[adjective]
Synonyms: unrewarding, fruitless, unappreciated, unprofitable, unrequited

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Antonyms: thankful
Contrasted words: appreciative, grateful, mindful, careful, heedful, thoughtful, thankworthy
Related Words: self-centered, careless, heedless, thoughtless, unappreciative, ungrateful, unmindful, disagreeable, distasteful, unpleasant, miserable, wretched

[TahlilGaran] English Synonym Dictionary ▲

thank‧less /ˈθæŋkləs/ adjective
[Word Family: noun: thanks, thankfulness; adjective: thankful, thankless; verb: thank; adverb: thankfully]
[Date: 1500-1600; Origin: thank (noun); ⇒ thanks²]

1. a thankless job is difficult and you do not get any praise for doing it
thankless task/job/chore etc
Cooking every day is a thankless task.

2. literary a thankless person is not grateful

[TahlilGaran] Dictionary of Contemporary English ▲