Apparently you can pronounce turmeric with and without the first r and still be correct. It's only recently that the spelling's been standardized, too: in the past, it took on forms like tarmaluk, tamanick, tamaret, tormarith, turmerocke, and more. When the word was first used in English in a 1538 book about herbs, it was spelled tormeryke, and that is thought to come from the Old French term terre merite, which meant "deserving earth" (although that's somewhat debated; it could also be Arabic). Terre comes from Latin terra, which is a relatively common root and further derives from Proto-Indo-European ters, meaning "dry". Merite is from Latin meritus, which meant "earned" and is the source of our word merit. That in turn traces to PIE mer, "to assign". Usage of the word turmeric has been pretty constant since the eighteenth century.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.