Definition of thankless:
bad, rude, objectionable, ingratitude, bleak, unvalued, unpleasant, unthankful, profitless, churlish, take someone for granted, ungratifying, harsh, barren, cruel, self-centered, unthanking, disagreeable, grateful, hard, useless, unsung, repay, vain, unappreciative, unrewarding, ungrateful, awful, ungracious, unappreciated, unappealing, unattractive.
Rapt in thought, Fancy presents before his ravish'd eyes 100 Distant posterity, upon his page With transport dwelling; while bright learning's sons That ages hence must tread this earthly ball, Indignant, seem to curse the thankless age, That starved such merit.- "Poetical Works of Akenside", Mark Akenside.
- "The Grafters", Francis Lynde.
- "Georgian Poetry 1920-22", Various.