Best dictionary and thesaurus for me to buy for 2015 that isn't too expensive?

I'm an aspiring writer trying to expand on my vocabulary (which is very behind now that I've forgotten so much from school) and the dictionary I recently bought is very disappointing; it'll only have one definition for a word when the word itself will have at least one or two more commonly used definitions. So when making flash cards, I have to use my computer to be sure I have all of the common definitions. I really want to try and not use my computer to lookup words as I get distracted easily and it takes away my focus. With that in mind, what dictionary (and possibly a thesaurus) would you guys recommend for a poor minimum wage worker? :) Been researching the internet and supposed answers are very vague for me. I don't have a kindle and my phone is very outdated, so apps wont work for me.

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