This is feminine. The masculine form should be Sid. It reminds me of Sydney, which is feminine. And then of course you have the variant Sidney, which is masculine. It makes sense to me.
Syd Barrett comes to mind, that's how I know this name, but it's not the worst association. He was kinda crazy but he was cool. I like this name better than Sid, because it looks better, but it's an okay name either way.
One famous beares of this name is Syd Barrett (Real name: Roger Keith Barrett). He was the co-founder/singer/guitarist of the early Pink Floyd. Sadly enough his genius mind could not keep up with the life of a rockstar and quit the band after only 3 years.