Refers to a student or follower of a particular teacher, master, or school, often in traditional arts, scholarship, or martial arts. Slightly formal and somewhat old-fashioned; 弟子 (でし) is more common in everyday contexts.
He is a pupil of that famous calligrapher.
The master's disciples gathered and held an exhibition of their works.
Compound of 門 (gate, school of thought) and 人 (person), literally 'person of the gate', referring to someone who enters a teacher's gate to study.