adverb, adverb taking the 'to' particle, noun or participle which takes 'suru'
snugly; cosily; warm and comfortable
Describes a state of being warm and comfortable, often in a cozy place like under a blanket or in a heated room. Used adverbially with と or as a する-verb.
こたつでぬくぬくと過ごすのが好きだ。
I like spending time snugly in the kotatsu.
猫がストーブの前でぬくぬくしている。
The cat is lounging warmly in front of the heater.
adverb, adverb taking the 'to' particle
carefree; without hardship; living comfortably
Implies living or doing something easily, without effort or worry, sometimes with a nuance of being spoiled or taking it easy. Often used critically.
親のすねをかじってぬくぬくと暮らしている。
He's living carefreely off his parents.
ぬくぬくと育ったので苦労を知らない。
Having been raised without hardship, he doesn't know struggle.
noun which may take the genitive case particle 'no'
freshly made and still warm
Used attributively with の to describe food that is freshly prepared and still warm, emphasizing its appealing warmth.
ぬくぬくのパンを朝食に食べた。
I ate freshly baked, still-warm bread for breakfast.
adverb, adverb taking the 'to' particle
shamelessly; imprudently; brazenly
Rare usage; describes acting without shame or prudence, often in a self-satisfied manner. Can overlap with the carefree sense but emphasizes audacity.
彼は自分の失敗を棚に上げてぬくぬくと説教した。
He shamelessly lectured others while ignoring his own mistakes.