* 통통하다 (tongtonghada): This is a common and generally positive way to describe someone as chubby or plump. It suggests a healthy, slightly rounded appearance. It's often used for babies and young children.
* 포동포동하다 (podongpodonghada): Similar to 통통하다, but emphasizes a softer, more cuddly fullness. This is also often used for babies and young children.
* 살이 오르다 (sari oreuda): This literally means "to gain weight" or "to put on flesh." It's a more neutral description and can be used for adults as well, but it doesn't necessarily have the same cute connotation as the previous two.
* 뚱뚱하다 (ttungttunghada): This means "fat" or "obese," and is generally considered a less polite and potentially offensive term. Avoid using this unless you're very certain of the context and your relationship with the person you're describing.
For a child, 통통하다 (tongtonghada) or 포동포동하다 (podongpodonghada) are the safest and most appropriate choices. For an adult, consider the context carefully and err on the side of caution. Using 살이 오르다 (sari oreuda) might be a better alternative to 뚱뚱하다 (ttungttunghada).