ぬくぬく

ぬくぬく
adverb
snugly warm, comfortably
1. snugly warm, cozily
Comfortably warm, often in a sheltered environment.
I'm snuggled up warm in the futon.
To be cozy and warm in a heated room.
Even though it was snowing outside, the cat was snuggled up in the kotatsu.
2. living in comfort without hardship
Living an easy life without experiencing difficulties (often with slight negative nuance).
Raised in comfort without hardship.
Slightly negative nuance.
Living comfortably off their parents' money.
Negative nuance: implies living an easy life without effort.

ぬくぬく is an onomatopoeia describing cozy warmth or comfortable living.

SENSE 1 - PHYSICAL WARMTH:

SENSE 2 - SHELTERED LIFE (often negative):

VERBAL USE:
ぬくぬくする: to be cozy, to snuggle up

CONTRAST:

Note: Sense 2 can carry a critical nuance, implying someone is too comfortable and hasn't experienced real difficulties.