The word "徒弟" is formed by combining the character "徒", which means apprentice or follower and historically includes the radical "彳" (related to movement) and a phonetic component, with "弟", meaning younger brother and pictographically representing juniority. Together, they create a compound where "弟" specifies the subordinate role of the apprentice, literally denoting a follower who is like a younger brother in a learning relationship.