adverb, adverb taking the 'to' particle
Mimetic adverb describing a forceful, penetrating action such as stabbing, thrusting, or piercing. Often used with と.
ナイフがぐさりと刺さった。
The knife stabbed in deeply.
彼の言葉が胸にぐさりと突き刺さった。
His words pierced my heart deeply.