It's a polite and respectful term used for men who are older than the speaker. While it's not as formal as "sensei" or "shi-san", it's still considered respectful and appropriate to use when addressing someone older than yourself.
Here's a breakdown:
* Oji (おじ): This part means "uncle" or "older brother" in a general sense.
* San (さん): This is a respectful suffix added to names or titles, similar to "Mr." or "Ms." in English.
Therefore, "oji-san" essentially translates to "Mr. Uncle" or "Uncle (respectfully)."
It's worth noting that "oji-san" can sometimes carry a connotation of being slightly old-fashioned or even a bit grumpy, depending on the context.