The noun earnest has 1 sense (first 1 from tagged texts)
1. (1) earnest -- (something of value given by one person to another to bind a contract)
Overview of adj earnest
The adj earnest has 3 senses (first 1 from tagged texts)
1. (2) earnest, sincere, solemn -- (characterized by a firm and humorless belief in the validity of your opinions; "both sides were deeply in earnest, even passionate"; "an entirely sincere and cruel tyrant"; "a film with a solemn social message")
2. dear, devout, earnest, heartfelt -- (earnest; "one's dearest wish"; "devout wishes for their success"; "heartfelt condolences")
3. businesslike, earnest -- (not distracted by anything unrelated to the goal)