adverb, adverb taking the 'to' particle
Indicates that something has changed fully or that a state is absolute. Often used when a situation has transformed completely, or when someone has forgotten or finished something entirely.
彼のことはすっかり忘れていた。
I had completely forgotten about him.
春になって雪がすっかり溶けた。
Spring came and the snow melted completely.
準備はすっかり整いました。
The preparations are completely ready.
I completely forgot about the homework.
This town has changed completely.
He has become completely healthy again.
すっかり is a neutral everyday adverb meaning 'completely', whereas 根こそぎ adds a nuance of thorough removal or destruction, often with a negative connotation.
すっかり means simply 'completely' with no attitude implied, while けろり adds a sense of surprising suddenness or nonchalance.
すっかり typically describes a complete change of state (e.g. すっかり忘れた 'completely forgot'), while 丸々 focuses on an entire quantity or duration being used or covered.
すっかり is a colloquial adverb for 'completely', often describing a change of state, while 残らず is slightly more formal and focuses on nothing being left behind.
すっかり means 'completely' or 'entirely' in a general sense, while すっきり means completely mainly when something undesirable has disappeared or been cleared away.
すっかり means "completely" in a plain, neutral way, while からり in this sense keeps a light, breezy onomatopoeic feel even when meaning the same thing.