The Oxford Thesaurus An A-Z Dictionary of Synonyms - earnest adj.

1) serious, solemn, grave, sober, intense, steady, resolute, resolved, firm, determined, assiduous, sincere, dedicated, committed, devoted, thoughtful: He made an earnest promise to do his best. 2) zealous, ardent, diligent, assiduous, industrious, hard-working, devoted, eager, conscientious, keen, fervent, fervid, enthusiastic, passionate: Burbridge is an earnest pupil. 3) earnest-money. deposit, down payment, binder, handsel, guarantee, security, pledge: The company paid њ10,000 earnest-money to secure the bid. --n. 4) in earnest. serious, sincere: She said she would come, but I doubt whether she was in earnest.