adverb.
In an earnest manner; being very sincere; putting forth genuine effort.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adverb.
in a serious manner
Word Usage
"Melissa Hathaway, President Obama's go-to adviser on cybersecurity, issued a rallying cry for the tech security community to begin earnestly collaborating on a "holistic approach" to slow rising cyber threats."