The word rapper consists of an idea word and a suffix "-er". Rap means "rap" and the suffix "-er" is usually translated as "singer", so rapper means "rapper".
Generally speaking, adding the suffix "-er" after a word can indicate the corresponding occupation. Such as teachers, cleaners, workers and travelers.
Extended data:
The suffix -er not only means "people", but also other meaning:
1. Representation (something related to something or something that can do something) and animals (animals that can do something)
Such as: washing machine washing machine; Five five-dollar bills; Lighter lighter; Ten-pound notes; Heater heater; Muffler muffler; Cutter cutter; Woodpecker woodpecker; Boiler boiler; reptile
2. Add it to the position word to indicate "... wind"
Strong north wind; Souther's strong south wind; Strong northwest wind; Southeast wind is stronger than southeast wind;
3. Adjective and adverb suffixes
It means that the comparative degree is "more ……" For example, the bigger, the bigger; The sooner the better; Warmer and warmer; Earlier is earlier; Being happier is being happier; The harder you work, the harder you work.