This is the generic word used in Hawaiian for any type of gardenia. I do believe this is a form of an older Polynesian word (tiale) and you can see the similarity in its sound with the name of the Tahitian gardenia that we see a lot of here in Hawai'i, tiare (roll the r on this one, please!).
Many people do not know, however, that Hawaiʻi has a native gardenia of its very own, that is not found anywhere else (it's endemic to Hawaiʻi). It is known as nānū or nāʻū. Fortunately, after being endangered in the wild for so long (which prevented its propogation for home use), it was fairly recently put on the list of endangered plants that can be propogated and grown in gardens. So that means that you can search out nurseries, buy a nāʻū plant and grow it at home! How special is that? You would help save this endangered plant AND have a sweet smelling flower. Its scent, like all kiele varieties, is exquisite! If you can get by the cost (upwards of $15) then it would surely be considered an investment in our 'āina.