Definition of in earnest
1
: in an earnest or serious way
- The search began in earnest when the police arrived.
- After light showers during the day, it began to rain in earnest in the evening.
- It's hard to tell if he's making this proposal in earnest.
2
: not fooling : serious and sincere
- We thought he was joking at first, but then we realized that he was in earnest.
