残のこらず

の

こ

ら

ず

Common wordJLPTN2

Meanings

1

adverb

Used adverbially to mean that nothing is left out; often implies thoroughness or totality.

その

本ほん

は

残のこ

ら

ず

売う

り

切き

れ

た

。

The book sold out completely.

全ぜん部ぶ
全部 is a noun meaning 'all' or 'the whole', while 残らず is an adverb emphasizing that nothing remains or is omitted.
すっかり
すっかり is a more colloquial adverb for 'completely', often used for changes of state, while 残らず is slightly more formal and focuses on the absence of leftovers.

Adverbial form of the verb 残る (のこる, 'to remain'), literally meaning 'without remaining'.