The first time we come across the word disciple in the New Testament is in Matthew 5:1. The Greek word "mathetes" is translated as “disciples.” It is used and translated some 269 times in the rest of the New Testament. In general usage, this word “denotes the man who directs his mind to something.” Very early in its usage this word took on the sense of pupil. The emphasis seems to be on the fact that one so designated as a "disciple" is engaged in learning.
The oldest usage and description of this word is in relationship to a man named Anacharsis, where he is called "the disciple." In this sense he is said to have adopted Greek wisdom and culture, and has become their champion. According to the Theological Dictionary of Greek Words, the emphasis is never on the deficiency of knowledge or learning, but the emphasis is on the fact that one is engaged in learning. Also, important to note, is that the education process or learning process consists of specific knowledge or conduct, and that it proceeds from a deliberate and set plan. Secondly, it is also important to note that there is a direct implication of dependence of the person who is under instruction upon a person of superior character of knowledge. Mathetes is the usual word for an apprentice. There is a very close bond between the discipler and the disciple. There is a close fellowship that developed over time. This relationship became so close that rarely did groups who met around various teachers disintegrate if and when the primary teacher or discipler died. We see this with the disciples of Jesus. Yes, for a short time they returned home discouraged, defeated, and depressed. But they reassembled and later it was said in Acts that they turned the world upside down. Now our word occurs primarily in the gospels and the book of Acts, as I said some 269 times. For the most part it is used of the men who attached themselves to Jesus. It is used of the men who attached themselves to John the Baptist, Paul, and of some who followed Jesus. This term came to be applied to believers, believers who followed Jesus, His teachings, and His doctrine. What is significant about this term, it describes a very personal and indissoluble union. These men in the NT committed themselves to Jesus.