Does reducing the clear juice from tomatoes have a name? I have been cooking a very light tomato topping for tortellini using dicing tomatoes.  I saute them very briefly until the flesh begins to soften, then remove the pieces from the pan leaving whatever juice cooked out of the tomatoes there.  This liquid is then reduced until it is a syrup, and recombined with the pieces.

Does this technique have a name?  Is it weird?
You've already given the name for this process in your question. Reduction is the cooking term used for thickening and intensifying the flavor of a food by simmering or boiling away some of the liquid.