“Sir” is one of three ways to translate the Greek word kyrios. That word can also mean “master” and “Lord.” It is hard to know exactly how the individuals in the gospel records addressed Jesus (Yeshua‘). It might have been with the deep respect of a master or the reverence of the Lord. In some cases, they were probably just speaking politely, “Sir.”
Sir in Greek:
Kyrie
Strong’s Concordance number: 2962
Bible references: John 4:11, 15, 19, 49; 5:7; 20:15 (eleven times in total).
The woman [at the well of Samaria] saith unto him, Sir, thou hast nothing to draw with, and the well is deep: from whence then hast thou that living water? (John 4:11 KJV)
Kyrie is a form of the Greek word kyrios, which is most often translated “Lord” and occasionally “Master.”