adverb, adverb taking the 'to' particle, noun or participle which takes 'suru'
Describes uncomfortably hot and humid weather, often with a sense of stickiness. Used adverbially with する or と.
今日はむしむしして、汗が止まらない。
It's hot and humid today, and I can't stop sweating.
部屋がむしむしするので、エアコンをつけた。
The room was muggy, so I turned on the air conditioner.