An individal meeting with one or more individuals with the purpose of teaching believers how to win others to Christ, helping them grow spiritually and personally, and having them repeat the process with other believers by helping fulfill the Great Commission.

go and make disciples of all nations.
Matthew 28:19

...bringing every man up to his full maturity in Christ Jesus.
Colossians 1:28

Discipleship:

• is God centered (Matthew 6:33)
• is influenced by God's Word, the Bible (John 8:31-32)
• increases one's love for God and people (Mark 12:30-31)
• helps you become more like Jesus Christ (2 Corithians 3:18)
• involves spiritual multiplication (2 Timothy 2:2)