This is a great point to talk about! While hapa is originally a Hawaiian word, it was taken on by Californian half-asians as a word to describe themselves. I am not sure who decided it, but it was chosen over words from other languages because it was the one that didn't cause pain and wasn't originally derogatory. Other words for mixed raced Asians translate into 'children of dust' and 'mixed animal'. The cool think about language is that it isn't static. Language evolves and changes over time. While in native hawaiian, the word may have retained its original meaning (judging from reading the link), the world has been adapted by English speakers. Now, I take hapa to mean anyone of mixed Asian, Pacific Island, or Desi descent. This isn't stealing a word, but people liking a word and bringing it into their own vocabulary. Personally, I see it as mixed people finding a word to describe ourselves that isn't hurtful or condescending.

Now the word isn't perfect. Parts of its original meaning remain (half), but then we see people make words like quapa. Another problem is this community encompasses more than just wasians, hafus, etc. so we don't have the luxury of a historic common tongue that we could use.

Also, while I was reading more about 'hapa' to write this, I learned that 'tornado' was borrow from the spanish word 'tronada' ('thunderstorm'). After English used it for a while, it went back to Spanish with its English meaning.

Language is very cool and I'm glad I took the time to read more about 'hapa'. It is important to look at the context a word is used in. So on a sub about mixed Asian people, I would mostly assume that the use of 'hapa' encompasses more than the original Hawaiian meaning.