That's the definition as I understand it.
Wiki-here I come!
A
roadster, also known as a
spyder or
spider, is a two-seater car, traditionally without a roof (or with a detachable roof) and no side or rear windows. Modern day two-seaters commonly have windows and feature retractable roofs (and are thus
convertibles). While retractable soft-tops are still marketed as roadsters/spyders, retractable hard-tops are commonly designated as
coupe roadsters.
Or:
A
convertible is a type of automobile in which the roof can retract and fold away, converting it from an enclosed to an open-air vehicle. Many different
automobile body styles are manufactured and marketed in convertible form.
Roof designs vary widely, but a few characteristics are common to all convertibles. Roofs are affixed to the body of the vehicle and are usually not detachable. Instead the roof is hinged and folds away, either into a recess behind the rear seats or into the boot or trunk of the vehicle. The roof may operate either manually or automatically via hydraulic or electrical actuators, and the roof itself may be constructed of soft or rigid material. Soft-tops are made of vinyl, canvas or other textile material, while hard-tops are made of steel, aluminum, plastic or other rigid materials.
Contemporary convertibles are known and marketed under several different terms due to the convergence of body styles over the years. A soft-top convertible may also be referred to as a
cabriolet, although two-seater soft tops often retain the name
roadster, referring to their body style. Hard-tops are marketed under the terms
coupé cabriolet,
coupé convertible or simply
retractable hardtop, while two-seaters more commonly use
coupé roadster/
roadster coupé.
I think that since our cars give the
appearance of a detachable roof, I'll call it a roadster!