This is a good topic, and one that is not clear for many people.
NOS is as stated -
New Old Stock or others state it as
New Obsolete Stock.
Age is relevant, as generally the item is no longer being produced / manufactured.
Basically, it is stock that has never been sold in the retail environment.
I have to disagree with Harris on this one though -
NOS is different than condition. You can have an NOS item that is only say 6/10 (a scratched number plate in a sealed packet).
Also many items are not in packets and never where. So, an item does not have to be in a packet to be NOS. An example could be a sew on patch, this is NOS but may also be slighty faded. These are again NOS but may be in 8/10 condition etc.
Once any item has been built / installed / used it can not be NOS, but can be in 10/10 condition.
As an example a bike could be built from all NOS parts, and the condition 10/10, mint, etc etc (whatever term is used) but if stripped and the parts re-sold they can not be classed as NOS. This is officially braking the law (trade description act etc).
There are many of ways to label parts as in MB (mint in box), AMB (almost mint in box), M (mint un-boxed), VSC (very slightly chipped), P (poor) etc and many inbetween - I can list all if anyone is interested.
Personally, in the BMX scene a definition is needed. It is too easy to state NOS (and you buy an item and find it is a lot worse condition that you'd expected), when what you would have been happy with / preffered was a mint item in a damaged box that was not NOS. I for one have had a falling out with a member on here from buying some items that (in my opinion) had a false description.
Also an NOS item bought from say Jim Melton, that was then sold by a collector to another collector can not techically be NOS as it has entered the retail market (but we will not go there
). It can be unused and new in 10/10 condition, but is no longer New Old Stock as it is current stock (it has been sold by the manufacturer, distributor, agent etc) and is now in the market place, like antiques.
J.