adverb, adverb taking the 'to' particle, noun or participle which takes 'suru'
Describes a close, tight fit without gaps, often used for clothing, lids, or schedules. Mimetic word that can take と or する.
この帽子はぴっちりと頭に合う。
This hat fits snugly on my head.
スケジュールがぴっちり詰まっている。
My schedule is packed tight.