The English word "apostle" comes from the Greek term apostolos, which means a messenger, envoy, or ambassador. Related to the verb, "to send," it refers to one who is "sent" on behalf of another.

The term "apostle" in the New Testament is used primarily to designate that group of leaders within the early church(es) who were historical witnesses of the resurrected Lord and proclaimers of God's saving mercies enacted through the death and resurrection of Jesus. Jesus originally gave the title to His closest circle of friends, the twelve (Luke 6:13).

The term "disciple" comes to us in English from a Latin root. Its basic meaning is "learner" or "pupil." The term is virtually absent from the Old Testament, though there are two related references (1 Chron. 25:8; Isa. 8:16).

In the Greek world the word "disciple" normally referred to an adherent of a particular teacher or religious/philosophical school. It was the task of the disciple to learn, study, and pass along the sayings and teachings of the master. In rabbinic Judaism the term "disciple" referred to one who was committed to the interpretations of Scripture and religious tradition given him by the master or rabbi. Through a process of learning which would include a set meeting time and such pedagogical methods as question and answer, instruction, repetition, and memorization, the disciple would become increasingly devoted to the master and the master's teachings. In time, the disciple would, likewise, pass on the traditions to others.

The Gospels clearly show that the word "disciple" can refer to others besides the twelve. The verb "follow" became something of a technical term Jesus used to call His disciples, who were then called "followers," (Mark 4:10). These "followers" included a larger company of people from whom He selected the twelve (Mark 3:7-19; Luke 6:13-17). This larger group of disciples/followers included men and women (Luke 8:1-3; 23:49) from all walks of life. (Even the twelve included a variety: fishermen, a tax collector, a Zealot.) Jesus was no doubt especially popular among the socially outcast and religiously despised, but people of wealth and of theological training also followed (Luke 8:1-3; 19:1-10; John 3:1-3; 12:42; 19:38-39).

The Book of Acts frequently uses the term "disciple" to refer generally to all those who believe in the risen Lord (6:1-2,7; 9:1,10,19,26,38; 11:26,29). In addition, the verb form "to disciple" as it appears in the final commissioning scene of Matthew's Gospel (Matthew 28:19-20) also suggests a use in the early church of the term "disciple" as a more generalized name for all those who come to Jesus in faith, having heard and believed the gospel.

We have seen that, as references to the twelve, the words "apostle" and "disciple" could be synonymous. However, just as the term "disciple" could mean other followers of Jesus than the twelve in the time of His ministry, so also after His resurrection the term "disciple" had a wider meaning as well, being clearly applied to all His followers. Whereas the term "apostle" retained a more specific meaning, being tied to certain historical eyewitnesses of the resurrected Lord, the word "disciple" tended to lose its narrower associations with the twelve, and/or those who followed the historical Jesus, or who saw the risen Lord, and became a virtual equivalent to "Christian" (Acts 11:26). In every case, however, the common bond of meaning for the various applications of the word "disciple" was allegiance to Jesus.

This information is an excerpt from the Holman Bible Dictionary.