The word "synthetic" in simple association with "oil", is meaningless, and has been for many years.
IF the oil is an API defined Group IV, then it's for sure a synthetic by virtue of it being a polyalphaolefin, aka "PAO".
If the oil is an API defined Group V basket of everything other than Groups I, II, III, & IV, it's still no guarantee, as for example, castor bean plant seed oil is a Group V by virtue on it not being a I, II, III or IV.
Many Group III oils are called "synthetic", yet they are all mineral oils, and remain as mineral oils, although are highly processed and have higher Viscosity Index (VI) numbers.
(Both Germany and Japan exclude the use of the term "synthetic" for Group III oils, and I think that stemmed from the somewhat famous Castrol vs. Mobil lawsuit of years ago.)
The reality is, that the majority, and likely the vast majority, of engine oils badged as being synthetic, have not been synthesized at all, and instead are highly processed mineral oils. That's not to say they are no good, but they sure aren't "synthetic".
I have not checked, but I think the Mobil 1 motorcycle oil is a Group III, and therefore not synthetic as it hasn't been synthesized.