idly
idle + -ly
https://gyazo.com/34d3d6050e88bb4524f7b1942fb60215
source: [日常の相生祐子が部屋で寝転がってぼーっとしているGIF画像｜無料GIF画像検索 GIFMAGAZINE 92723]
adverb
with no particular purpose, reason, or foundation:
何もしないで; 当てもなく
e.g. “How was the game?” Katie asked idly.
in an inactive or lazy way:
怠けて
e.g. I can no longer stand idly by and let him take the blame.