ぷくぷく

A mimetic word with two distinct senses. The "plump" sense is affectionate and positive — it suggests healthy roundness, not obesity. The "bubbling" sense directly imitates the sound and appearance of small bubbles.

Grammatical forms

• ぷくぷくした — plump (modifier before nouns)
• ぷくぷくに太(ふと)る — to get chubby
• ぷくぷくと泡(あわ)が出(で)る — bubbles come up

Similar onomatopoeia

• ぽっちゃり — plump, slightly chubby (for people; more neutral/adult usage)
• ぶくぶく — swelling up; bloated (negative nuance, unlike ぷくぷく)
• ぐつぐつ — boiling vigorously (stronger bubbling than ぷくぷく)
• ぶくぶく — bubbling heavily (larger bubbles than ぷくぷく)

Usage

The ぷ sound in Japanese often evokes softness and roundness. ぷくぷく is almost always used positively or neutrally. For a negative "getting fat," Japanese speakers would more likely use ぶくぶく instead.