What is meaningful work?

As Teresa Amabile and Steven Kramer have shown, making progress in work that is meaningful is one of the most motivating, if not the most motivating, things in work. Even small progress may have a big positive impact on one's inner work life (this is the authors' term for perception, emotions and motivations in one's work).

'Meaningful progress', of course, consists of two parts: the meaningful part and the progress part. I have focused a lot on the progress element in many previous posts. I'd now like to focus on the meaningful part.

I am interested in what makes work meaningful for people. What dimensions underlie meaningfulness? I suspect that meaningfulness can be largely explained by the degree to which the work offers opportunities for fulfillment of the well known basic psychological needs of autonomy, competence and relatedness. Is this right? Or is meaningfulness of work importantly related to intrinsic motivation? To what extent do the interestingness and enjoyability of the work activities themselves determine meaningfulness?

Or do other factors play an important role? For instance being helpful to other people or humanity as a whole (or even beyond that: making a valuable contribution to 'the world'). Or are such things really aspects of relatedness?

Questions: What are your views on these matters? What makes your work meaningful to you? Have you ever been able to make your work more meaningful? How did you do that?