"Fatso" is a derogatory term used to describe someone who is overweight. It is not only offensive but also unkind to use such a word to describe someone. Instead of using "fatso", try selecting synonyms that are more respectful and polite. For instance, you can use words like "plump", "portly", "curvy" or "rotund". "Chubby", "full-figured" and "well-built" can also be employed as alternatives. Keep in mind that everyone, regardless of their body shape, deserves respect and kindness. Avoid using any derogatory term when describing someone's physical appearance. Instead, choose words that are inclusive and gentle.