Is there a dictionary website out there that will let me check definitions for multiple words at once? For example, I want to upload a comma or new-line separated list of words have it return all the definitions.
Try this: OneLook Dictionary Search
I checked it out but it doesn't offer the functionality I described.
Did you try with Boolean search terms?
I prefer to use Dictionary.com
that's very useful website
You can do that here: Ninjawords - a really fast dictionary