The very serious Oxford dictionaries Oxford announced Thursday to have added this year 500 new words one of which is of particular interest to us : « E-cigarette". It is thus defined in this way:
an e-cigarette: a cigarette-shaped device containing a nicotine-based liquid or other substances that are vaporized and inhaled in order to simulate the smoking experience".
Even if the definition presented is a little surprising, one will be satisfied to appreciate the presence of the word "E-cigarette" in such a document.
source : Oxford Dictionaries