[F,A,I,R] -> [possible, plausible, probable, perishable]
Findability is making reuse possible. If no one can discover your data, if even basic metadata is hidden in a silo, then reuse is simply not possible.
Accessibility is making reuse plausible. People and their designated software agents can not only identify relevant resources via metadata, but they can actually retrieve full data for inspection and evaluation.
Interoperability is making reuse probable. Not only is your data findable and accessible, but there is not too heavy a burden on someone to make your data compatible with their own data and processing tools. Your data is accessible in an open, standard format. You include a schema with the data, preferably in a machine-actionable format as well. An interested consumer is significantly more likely to bite.
Reusability, finally, is making reuse…perishable. Using a food analogy, let’s say you have identified a potential ingredient for a recipe (findability); you know it is in stock at a nearby store (accessibility); and you have determined that it is indeed suitable for use with your kitchen tools, other ingredients you have on-hand for the recipe, etc. (interoperability). Finally, you can bring it home to your kitchen…but will you actually be able to use it?