Nix. The "O" is for "Octo", 8, and refer to the number of elements. It is also NOT a 'Micro-Nikkor', as correctly pointed out by Erik.
This practice of marking the lenses according to number of elements was used by Nikon for many decades, so nothing special with the Nikkor-O 55/1.2.
Nikon stopped this labelling somewhere in the late '70s. Perhaps the lens designs then became complex enough without the added Latin specifier, or people no longer cared, or they tried to save money on engraving, or what do I know.
Back to the Oscilloscope lens. I have been ruminating through my clippings files to find the photo of the first Oscilloscope lens I saw on a Nikon camera, but to no avail. I distinctly recall the article reported its effective aperture was not the marked f/1.2, but f/1.4, as (we know by now) f-numbers are always defined for infinity focus and this was 1:4.4. The outline of that lens was more similar to the first-generation Nikkors having scalloped rings and chrome barrel. What I did find, however, were several brochures showing the Oscilloscope rig as part of a Nikon F system. These were from around 1969 and obviously the intended lens had to be in direct F mount or mounted by using the BR-15 adapter.
My analysis based on the meagre data available is as follows: Initially, early '60s, there was an industrial lens design for capturing traces on CRT displays such as the then contemporary oscilloscopes. A fast lens was required due to the weak traces and its curvature of field had to be "negative" to compensate for the curvature of the CRT surface to give sharpness all over the frame. This first model was the Nikkor-O 55 mm f/1.2. I can only guess what kind of camera or measuring device these first models aimed at. Perhaps they figured as an optical component of a large device recording oscilloscope traces on cine film and the long 39 mm Leica thread and its locking nut was used to align the focus and then secure it for production runs? This model must have been replaced by a similar lens using F-mount and the outward appearance of a 'normal' (50mm) Nikkor of the time. Repair facilities still have similar-looking items used for calibration and testing, these typically lack focusing helicoid. It might be the latter model that had the designation 'Oscilloscope-Nikkor' and was referred to in the article clipping I still haven't found. I do recall it was published in a Swedish photomagazine in the late '60s, though.
