noun
intermediate-level person; intermediate student/learner/practitioner
Refers to someone who has moved past the beginner stage but is not yet advanced. Used in educational, hobby, sports, and skill contexts.
このクラスは中級者向けです。
This class is for intermediate-level students.
彼はテニスの中級者だ。
He is an intermediate tennis player.
上級者 means 'advanced-level person', the stage beyond 中級者.
Compound of 中級 (intermediate level) + 者 (person). The exact historical derivation is straightforward; the word follows a common pattern for describing proficiency levels.