There's a Greek root behind this, namely sumphora, mishap or calamity, but whether the English adjective comes from a Greek one or was derived from the noun is unclear. Either way, it's another word that could use a little love. I mean, you can just imagine it blundering through the dictionary, stumbling over half the instruments of a symphony as it tries to find its seat on the page. Poor little word. I don't know when it entered the language, but I found a citation as far back as 1781, from Jeremy Bentham, who didn't think much of it:
"Who would have endured in this place to have seen two such words as the phthano-paranomic or crime-preventing, and the phthano-symphoric or calamity-preventing, branches of the police?"