Losing the Routine

I lost the habit of doing the Spanish study everyday, so now my program tells me I'm looking at 5 or so hours of work to catch up. When this sort of thing happens, I get a bit more bugged about not knowing how important each word is. If I'm learning a word I'll never use, I'm essentially wasting time, except for the fun stuff learning that word does to my brain- but then I could be learning some other word instead.
It occured to me that I could pull the most used words right out of the dictionary. Trouble is, I'd have to troll through all the definitions in order to find out which words they are. Words used most often to define other words ought to be the most used words (except for those words specific to the dictionary vernacular), though sometimes we end up with circular definitions in which one word defines another and vice versa.
If you want an interesting excercise, think of a word. Then go to the dictionary and write out its definition. Then look up every word in the definition and put it in parenthesis (like an equation) under each word. You will quite quickly end up with gibberish and/or the word you started with in your definition/equation. Words are poor definitions for other words- it's far better to point to a chair instead of trying to use words to define a chair.

This works(or doesn't, depending on how you see it)no matter what your definition of is is.