I tend not to think of words like this as, well, words. Instead, I think of them as abbreviations or as, indeed, prefixes. On the other hand, the definition and the usage clearly indicates that it is a word as well as an abbreviation.
a. colloq. Aerodynamic, streamlined: used chiefly with reference to motor vehicles.
b. Comb. aero bar Cycling, an attachment to or replacement for the handlebars of a racing bicycle, allowing the cyclist to adopt a more aerodynamic, forward-sitting posture.
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