A few standard ebay acronyms:
NIB - New In Box
NOS - New Old Stock
(B)NW[0]T -(brand) New With [out] Tag
OEM - Original Equipment Manufacturer -- either 1 ) this is genuine, not aftermarket replacement, or 2 ) this is as it would be supplied to a producer, not a retailer: same item, plain cardboard box, no manuals, etc.