noun
Refers to the philosophy or practice of engaging in an activity, especially sports or arts, as an amateur rather than a professional.
彼はアマチュアリズムを大切にして、賞金を受け取らなかった。
He valued amateurism and did not accept prize money.
アマチュア is a noun/adjective meaning 'amateur' (a person or non-professional status), while アマチュアリズム is the abstract concept or ideology of amateurism.
Antonym: professionalism, the conduct or qualities expected of a professional.
Borrowed from English 'amateurism', combining 'amateur' with the suffix '-ism'.