1. I-adjective (keiyoushi)

   sluggish; languid; listless; heavy (heart, legs, etc.); dull

   Usually written using kana alone

   だるいし頭がずきずきする。

2. bothersome; tiresome; pain-in-the-ass

   Usually written using kana aloneSlang

Also written 懈い【だるい】darui