adverb taking the 'to' particle
Mimetic word describing a soft, plump, or slightly chubby appearance, often with a cute or appealing nuance. Related to ムチムチ, but ムチッ suggests a more compact or momentary impression.
See also: ムチムチ
その赤ちゃんのほっぺたはムチッとしていて、触りたくなる。
That baby's cheeks are so plump and soft you just want to touch them.
彼女はムチッとした体型が魅力的だ。
Her plump figure is charming.