1. in a way that shows a loss of mental faculties; insanely or crazily
Usage: often used to describe behavior that appears irrational or frenzied

Examples

• He laughed dementedly as he ran through the streets.
• She was waving her arms dementedly, trying to get someone's attention.
• The character in the horror film screamed dementedly before disappearing into the darkness.
• He dementedly insisted that the conspiracy was real, despite all evidence to the contrary.
• The crowd cheered dementedly when their team scored the winning goal.