1. in a manner that is foolish, silly, or lacking in intelligence or awareness
Usage: derived from the adjective 'fatuous'

Examples

• He fatuously assumed that everyone would agree with his plan without any discussion.
• She smiled fatuously at the joke, not understanding the humor at all.
• The candidate fatuously claimed he could solve all economic problems in a week.
• He nodded fatuously, pretending to comprehend the complex scientific explanation.
• The character fatuously believed that money could buy happiness and nothing else mattered.
• She laughed fatuously at her own remarks, oblivious to how they sounded to others.