Via this Usable Help blog post, comes a great article lucidly describing how to understand Engineers when it comes to feasibility.
If you want a clear and simple discussion of the terms impossible, trivial, unfeasible, non-trivial, hard, and very hard from an engineer's perspective, then you should definitely check it out.
One misunderstanding by some non-engineers is how the word 'trivial' is used. In our discussions, trivial just means that we know the solution to a specific problem. It doesn't mean that the implementation of that solution is necessarily easy. So for example, the design of a specific portion of a structure might be trivial but actually building it might be a nightmare.
It's definitely an interesting read for anyone involved with solving problems - isn't that all of us? ;)