This question asks for a term describing a civilization that eats others to gain their assets. It's an interesting question and clearly related to worldbuilding. I would argue that worldbuilding is not the best fit for this question though and I think it would do better on either English Language & Usage or Science Fiction & Fantasy.
The way I see it, this is not a question about worldbuilding, but rather a question related to worldbuilding. I suppose it's up to the community to decide if questions like these should be within the scope of this site.