If you're investing/buying a product, it would be good to clarify with the seller what their definition is, as it's relatively subjective. I would agree with the definition here of short = less than 1 year, medium = 1 to 4 years, long = 5 years and beyond.
I dont need to know what my ideas of time scale for investing are. Really what I'm asking is, Company X says "tough trading conditions in short term", how long is this short term or company Y says "hope to start paying dividend in medium term" again when?