"Chap" is a slang term used to refer to a man or a boy. However, there are various synonyms that can be used to replace this word depending on the context and the tone of the sentence. "Bloke" and "guy" are commonly used synonyms for "chap" especially in British English. "Fellow" is another more formal option that is often used in a polite conversation. For a more playful tone, terms such as "dude" or "fella" can be used. "Boy" and "lad" are also synonyms that can be used for younger individuals. "Bro" is a modern slang term that is also used in informal contexts as a synonym for "chap".