Synonyms of thankless

1 Syllable
vain
2 Syllables
barren, fruitless, wretched
3 Syllables
useless, unpleasant, futile
4 Syllables
distasteful, unwelcome, disagreeable, miserable, unrewarding, ungrateful, ungraciousness, undesired, unwished-for, unrequited, unreturned
5 Syllables
unwelcomeness, unrecognized, unprofitable
6 Syllables
inhospitality, inhospitableness