William Duffield
The question "What is jacaranda?" is about as enlightening as "What is ironwood?" You may as well answer "42."

Yes, Brazilian rosewood" is one valid answer. On the dry side of Cuba, there is a small tree/large shrub called jacaranda that looks like a rosewood, with almost black heartwood and almost white sapwood. There is another legume tree that grows as far north as Central Florida, with smooth white bark, blue flowers and large, heavy bean pods that are tightly curved and distorted, resulting in another common name, "ear tree." I'm sure there are other examples, but less ambiguous scientific names are difficult to nail down. None of the "jacaranda" woods that I have encountered look anything like Derek's example, so his may be a native eucalypt.