1. in a manner that is excessively or unnecessarily earnest; with more seriousness or intensity than is appropriate or warranted
Usage: informal; typically used to describe behavior or speech that is overly sincere or grave

Examples

• He overearnestly explained the rules of the game, turning a simple activity into a tedious lecture.
• She spoke overearnestly about the importance of recycling, making everyone uncomfortable with her intensity.
• The young actor delivered his lines overearnestly, lacking the subtlety the director had requested.
• He overearnestly apologized for a minor mistake, making the situation more awkward than necessary.
• The teacher overearnestly warned the class about the dangers of procrastination, as if it were a life-or-death matter.