The term authenticity is used to describe music, philosophy, education, art, writing, assessment, and motivation.  How could one term cover so many fields?  I decided to look into the word's origin, here is what I found...

Descartes first proposed the idea of authenticity as following a moral inner voice; and, according to this voice, individuals must think and act responsibly.  The notion of identity before Descartes was that an individual's morality was developed through their status in society, and from sources external of the body.

Rousseau supported Descartes by saying that moral sense and authenticity is a voice of nature within us.  Herder takes this idea and extrapolates that creativity, authenticity, and originality are measures of existence.  Meaning that our identity is based on experiences and how we interpret those experiences. 

A very subtle, yet distinct transition occurs between these three

philosophers.  The notion of authenticity changes from an external force, to an inner voice, and finally to an inner voice that is developed through experience.(1)    

Grimmett combines the ideas of these three philosophers and says that, authenticity is "to draw on a 'body' of knowledge and to speak and act from those moral spaces with a confidence that is rooted in a conscious, collective understanding."(2)

Grimmett's definition of authenticity and the current notion of authentic learning both explicitly state that knowledge (whether it be moral knowledge or informational knowledge) is based on consciousness, experience, and reflection.

Here are some sites that I founds useful when I first searched for the meaning of authenticity.  Hopefully, they will help you as much as they helped did me!

Students become experts on the web.

Catalytic and tactical authenticity in research.

Tiffany Marra