"Opa" is very easy to learn to pronounce, and not surprisingly is used in many languages to get the attention of some of the more important people a young child may need help from. Many many languages use ma and pa/ba for parents, and I'm not surprised that opa is used for other relatives by many languages.
I'm not Korean, but my understanding is one reading might be "Mister Language". Several of my Korean friends address me as "Karl Oppa" or just "Oppa". (Yes, "opa" isn't the standard Romanization, and the word order isn't correct.)
In Korean "oppa" is the word for older brother used by a younger sister, and by extension, an honorific used by a younger woman to show respect for an older man. (When my Korean friends meet someone new, they quickly figure out who's older, even by just one year, in order to figure out who's supposed to use the honorific addresses.)
Imagine if in English, we only used Mr. and Ms. when talking to someone who's chronologically older, and had different forms depending on if the speaker is male or female, and furthermore it was considered very rude not to use the title where appropriate. Oppa is kind of the word for "mister" used by women, but is mandatory in many more cases than would be expected in English.
> Imagine if in English, we only used Mr. and Ms. when talking to someone who's chronologically older, and had different forms depending on if the speaker is male or female, and furthermore it was considered very rude not to use the title where appropriate.
In parts of the South, you’re still expected to use “sir” and “ma’am”, particularly with strangers. Most speakers find this a bit old-fashioned or excessively polite, though.
It always irks me, I don't know when this trend started but when I moved away from Korea in the mid 90s as a young child this was strictly a honorific for older brother from a younger sister OR maybe I was just unaware of the trend because I was a kid.
So I get grossed out when a Korean girl calls me oppa and I have expressed my discomfort which was met with a cold response (I guess they really like calling older men oppa), part of the reason I never date younger Korean women. That and the whole 'mister' or aekyo (adult women emulating an infant) shit I find very creepy and unattractive. There's this national inclination for young women, sort of like Japan's obsession with schoolgirls.
On the other hand, being called 'ajusshi' which doesn't carry the same affection as 'oppa' and intended for much older men and some Korean men take offense when addressed as 'ajusshi' but less so than Korean women who go apeshit when I made the mistake of calling them 'ajumma'.
on an offtopic side note, Oppai in Japanese means tits.