and additionally i have found this article which actually defines power leveling by blizzard’s own legal terms; “Power leveling: is the term used to describe the process of leveling a character as rapidly as possible with the least amount of play time. It can be used from any level up to level cap. Contrary to what many believe, efficient power leveling does not require endless hours of grinding. The best methods of power leveling involve doing many [quests]”
The goal of these guides is to help you level a character, whether you’re first on the server or not, to the level of your choice as quickly and efficiently as possible. At the same time, the quests will be ordered in such fashion to ensure you gain [reputation] with each of the three major factions on either the [Alliance] or [Horde] side.
Common methods of power leveling include doing only those quests which are most efficient in terms of experience over time, and analyzing the quests in a given zone so as to do them in the most efficient order possible. Remember, the idea of power leveling is speed and efficiency–you may wish to obtain an addon that will show you how much experience per hour you are gaining to test your techniques. Additionally, ensure your character’s talent build is crafted for maximum endurance. You want as little downtime (walking, drinking, eating, crafting, typing, etc.) as possible.
With regard to [professions], an example would be for a [tailor] to [farm] or purchase large quantities of [cloth] then identify and repeat the cheapest tailoring recipes so as to maximize skill point gain compared to cost.
A twink is a well geared level 19 (29, 39, etc.) that usually stays that current level for battlegrounds
[Twinking] is distinct from power leveling. A twink is usually intended to remain at its current level for an extended period of time, thus providing some justification for the large investment into its gear. A character being power leveled is often equipped with inexpensive gear, since the [player] will be planning on outleveling it quickly."
“Also note that power leveling is sometimes used to refer to paying someone else to level your character to cap as fast as possible (i.e. they power level for you); a distinction used by Blizzard is to refer to the paid leveling as “power leveling service .” **This behavior is against Blizzard’s [Terms of Service]. Power leveling yourself, which this article covers, is perfectly acceptable.”