It depends on what translators choose to use.

Ven. Thanissaro's translation of [AN 8.26][1] says:

> "Lord, to what extent is one a lay follower?"

Ven. Sujato's translation of [AN 8.26][2] says:

> “Sir, how is a lay follower defined?” 

It turns out that the Pali sentence is:

> *“kittāvatā nu kho, bhante, upāsako hotī”ti?* 

In this case, the term "*bhante*" is translated as "lord" by Ven. Thanissaro and as "sir" by Ven. Sujato.

In this sutta ([MN 147][3]), "*bhante*" is translated as "venerable sir" by Ven. Bodhi.

Of course, "venerable sir" is the best translation.

Usually, the Buddha is addressed as "*bhante*" (venerable sir) in the second person and as "*bhagava*" (blessed one) in the third person.

This is in reference to Pali suttas.

  [1]: https://www.accesstoinsight.org/tipitaka/an/an08/an08.026.than.html
  [2]: http://suttacentral.net/an8.26/en/sujato
  [3]: https://suttacentral.net/mn147/en/bodhi