Are we going to split hairs about what constitutes a "singlespeed"? Does the bike in question have to have only one chainring and one cog? What about flip flop hubs? So a singlespeed would be one chainring and one cog or two cogs (but only one on each side of the hub)? Well, what about this dingle that Surly makes, or the Dos ENO freewheel? You could end up with a bike that has one chainring and four cogs. Is that not a singlespeed? Obviously, without derailleurs you can only use one chainring and one cog while in motion. So, effectively you have to chose a single speed for your particular ride.

Can I still call it a fixed gear bicycle even if I put a freewheel on the one side of my hub or do I have to have one cog and lockring on both sides of my fixed/fixed hub in order to call it a fixed gear? Or can I only call it a fixed gear while using the fixed cog?

Please let me know ASAP because this project can't continue until I know what kind of bike y'all are gonna let me build