earnest Look up earnest at Dictionary.com
O.E. eornoste (adj.) from a noun eornost "passion, zeal" (surviving only in the phrase in earnest), from P.Gmc. *ern "vigor, briskness" (cf. O.H.G. arnust "struggle," Goth. arniba "safely," O.N. jarna "fight, combat") The proper name Ernest (lit. "resolute") is from the same root.