All 4 Uses

earnest
in
Unbroken, by Hillenbrand
(Edited)

"It makes us very happy indeed to have performed this service for our prisoners and relatives and it is out [sic] earnest wish that no other such instances of this information will be forthcoming."
p. 255.2

earnest = sincere

editor's notes: "[Sic]" indicates that there was not a typo when this was written in the book. The word out was used when it should have been our.
You must work for earnest!
p. 288.3

earnest = real (with intensity)
He wrote earnest letters to her father, trying to win him over.
p. 342.8 *

earnest = sincere (deeply felt)
Describing Jesus rising from his knees after a night of prayer, Graham asked his listeners how long it had been since they'd prayed in earnest.
p. 373.1

in earnest = in a serious manner

Definitions:

(1) (earnest)
characterized by sincere belief

or:

intensely or excessively serious or determined
(2) (meaning too rare to warrant focus)
Earnest can also be used as a name (variant spelling of Ernest), or to signify the seriousness of a pledge made (as when earnest money is included with an offer to purchase a home).