Every law student worth her salt has a dog-eared, beat-up, underlined, and trampled legal dictionary. Nine times out of ten, that dictionary is Black's Law Dictionary. Black's, published by West, has a very good abridged edition which you should buy. The unabridged version, while not as weighty as the Oxford English Dictionary, is really an overkill.

During your first year, you should get into the habit of looking up every single legal word you don't know. It's also helpful to keep a list of these words for future reference. One of the difficulties of first year is recognizing that words that have normal meanings in plain English may have completely different legal meanings. For example in contracts the word consideration doesn't have anything to do with being polite and in Property, a fee simple is not an uncomplicated bill! If you can't make sense of a sentence, some legal words are most likely tripping you up.