a respectful way to address a teacher: my master, my teacher
Rabbi is a Hebrew word carried straight over into the Greek New Testament without being translated. It comes from a root meaning great or chief (רב), with an ending that originally meant my, so the plain sense is my great one and, by extension, my master. In the Gospels it is always a form of address, the word people say to someone's face out of respect.
When we hear rabbi today we picture an ordained, credentialed religious official belonging to a recognized profession. That is not what the word meant in Jesus's lifetime. At that point it was an informal, warm title of respect that almost anyone could pay to almost any teacher or notable person. The formal office, tied to ordination and to a defined class of scholars, only took shape gradually in the generations after the destruction of the Temple in 70 AD. So when Nicodemus, the disciples, a crowd, or a beggar calls Jesus rabbi, they are paying him the everyday courtesy due a recognized teacher, not enrolling him in a later profession.
The three senses below are not different meanings of the word. They are one honorific used in slightly different ways across the Gospels:
- the ordinary respectful address to a teacher
- the title held up and criticized as something people crave
- the loaded greeting Judas alone uses
The word itself stays the same throughout; what changes is who says it and why.