The Latin root of the word cicada, is cicada!
Looking back a bit farther, the Sanskrit word for cicada is चिश्चिर, which is pronounced cizcira. Not too big a leap from cizcira to cicada.
There are other similar Sanskrit and Latin words, for instance, 17 in Sanskrit is saptadaz, while 17 in Latin is septendecim. Sapta/septen, daz/decim — you can see the similarities.