I have been studying a bit about odors and plant essential oils. Several sources claim that the fragrant terpenes found in these oils, such as menthol, eugenol, limonene, linalool, etc. are volatile compounds.
I understand that all molecules are technically volatile, but since these molecules all have boiling points of over $170~\mathrm{^\circ C}$, and their vapor pressures are not particularly high, I don't see why they are considered 'volatile compounds'.
I have two guesses:
a) There is some fundamental aspect of chemistry that I am ignoring, and these compounds do have a set of properties that makes them especially volatile. This to me sounds very interesting, and I would really like to learn what is that makes these compounds especially well-made for being vaporized.
b) The compounds are not especially volatile. They are synthesized in large amounts, concentrated to high concentrations in the plant, and our nose is very sensitive to them. They are called 'volatile' compounds because we happen to notice their smell when they are in the air.
For my question I've chosen to focus on menthol. Is there anything about menthol that makes it especially volatile?