In the agency world, its a word you hear a lot.  In a consumer centric world it's what you NEED to be relevant to a collaborative audience.  For me it's a word I hear misused a lot.  

The dictionary defines it as:  penetrating mental vision or discernment; faculty of seeinginto inner character or underlying truth.

In psychological terms it is: 
an understanding of relationships that sheds light on orhelps solve a problem.

For those of us who create innovations, conversations and stories for on behalf of brands for people it means:

single human truth that motivates behavior.

In a big data world creating impact starts with synthesizing down to a single insight that inspires an idea and provokes an action.

The next time you sell an idea remember you only need truth to create an audacious provocation that could change the world.

Insight – Do you have one or not? via @jpenabickley