adverb, adverb taking the 'to' particle
Emphasizes that something is taken, removed, or disappears in its entirety, often with a sense of thoroughness or leaving nothing behind. Common with verbs like 取る, なくなる, 消える.
財布の中身をごっそり盗まれた。
The entire contents of my wallet were stolen.
冷蔵庫の食材がごっそりなくなっていた。
All the food in the fridge had completely disappeared.
adverb, adverb taking the 'to' particle
in large amounts; a lot
Used when a large quantity is moved, taken, or gathered at once, often with a nuance of bulk or sweeping action. Frequently appears with verbs like 持っていく, 買う, 集める.
彼はお菓子をごっそり買い込んだ。
He bought a whole bunch of snacks.
落ち葉をごっそり集めて袋に入れた。
I gathered up a large amount of fallen leaves and put them in a bag.
Mimetic word; the exact derivation is uncertain, but it likely belongs to a family of onomatopoeic adverbs with the pattern ごっ...り that express bulk or thoroughness.