it does not mean anything. They are Honda internal code designations (kinda like how GM uses F-body for pony cars and A-body for midsize cars). The very first preproduction hondas that were made carried A and B designations. When they went into production They were on their third version and so the C designation stuck. The second letter refers to different models or functions within the line. Think of it like software: you have version 1.1, 1.2, 1.3, 2.1, 2.2, etc. The letters do not actually stand for anything.
Overtime the C has taken on different meanings with different bikes (CR for example) but it's original meaning was road legal production bike with the B variants representing sports bikes, A representing standards, and L representing dual sports or scramblers. R was always racing variant so when coupled to C it just meant production racing bike. Latter honda would add an F to bikes it felt were more sporty based on a production road bike (cb750F, 550F, etc) with two exceptions: the cb350F and 400F where the F stood for four cylinder. What makes this harder is that inside the development name are other identifiers to signify upgraded versions or different year models (k0, k1, k2, cb350D, cb350E, etc....) to use the software analogy it is like version 1.2.1....well you get the idea.
All this talk that the letters actually stand for words are an urban legend, although it might be that the original prototype honda made carried the AA designation because that stood for something. That being said, all this stuff was developed in the 1940s and 50s before there was a us market and all the work was in Japanese and these bikes even carried the letter designations back then so the chance they stood for something in english is pretty thin. Plus the japanese use a different alphabet/characters from us in their native language. I doubt Mr. Honda himself was thinking about US distribution when building the first prototype in his house/shed.
currently the CBR designation is for sportbikes, RR is for production street legal race bikes (for built to comply with racing classes production rules) cb is for standards, and there are a whole host of other designations for off road.
The hardest part about figuring out what this means is that the meanings changed over the years. What CB meant in the 1960's and 70's is not the same as it meant in the 1980s.
