I am international engineering student studying in US. I have a question regarding words that are created as a result of joining two words. Usually this happens when two technologies or methodologies are used to create something unique (I am particularly interested in fusion of two words based on abstract ideas or technology). The confusion I have currently is "How to decide the proper word fusion?"
For example: Testbed vs test bed, feedforward vs feed forward vs feed-forward, etc.
I have this confusion because certain authors use certain fusion words. I would like to know if there is a universal rule or any guidance when I have to combine two words indicating abstract concepts.