adverb
with a clatter; loudly; flinging open
Describes the sound or action of something opening or moving noisily, often with a sliding or banging motion.
彼はガラッと戸を開けて入ってきた。
He flung the door open with a clatter and came in.
adverb
completely; dramatically; suddenly
Indicates a sudden, drastic change in state, appearance, or situation.
髪型を変えたら印象がガラッと変わった。
When I changed my hairstyle, my impression changed completely.