E-cigarettes were not commercially available until the 21st century, having been invented in China in 2003, yet the word vape actually dates to the early 1980s. Its earliest known use is in an article, “Why do People Smoke” in New Society in 1983. The author, Rob Stepney, described a hypothetical device being explored at the time:

“an inhaler or ‘non-combustible’ cigarette, looking much like the real thing, but…delivering a metered dose of nicotine vapour. (The new habit, if it catches on, would be known as vaping.)”

Thus, it seems that vaping the word existed before vaping the phenomenon. Oxford Dictionaries research indicates that while this sense of vape was in use in the 1990s, as evidenced by posts within the UseNet bulletin board system, it wasn’t until around 2009 that it started to appear regularly in mainstream sources.

[source: O.E.D]