Part of speech: Adverb
in a serious manner
Example: talking earnestly with his son; she started studying snakes in earnest; a play dealing seriously with the question of divorce
Badly, Severely, Seriously, In earnest, Gravely
serious – A related word in the same word family.
ly – A related word in the same word family.
English spelling is irregular because it preserves pronunciations from multiple historical periods simultaneously.