-er — one who, a person or thing that does (affix)

teacher A1

/ˈti.t͡ʃɚ/ A person whose job is to teach, especially in a school.

driver A1

/ˈdɹaɪvɚ/ A person who controls and operates a vehicle.

player A1

/ˈpleɪ.ɚ/ A person who takes part in a game or sport.

writer A1

/ˈɹaɪ.təɹ/ A person who writes books, stories, or articles, especially as a job.

worker A1

/ˈwɝ.kɚ/ A person who works at a particular job, especially physical work.

printer A2

/ˈpɹɪntɚ/ A machine connected to a computer that puts text or images onto paper.