<p>@SkyGirl: It depends. :)</p>
<p>Basically, there are two kinds of word knowledge. (I'm simplifying a little bit to keep things clear). One is productive knowledge: in other words, can you use the word in writing and speaking? The other is receptive knowledge: can you understand the word in reading, test taking, and listening? </p>
<p>If your goal is to build your reading and test-taking vocabulary, I think you are okay to just use the Barrons meanings. Put them on flash cards and you should be good to go--although I have to say that I find the Barrons list to be a little bit arbitrary; it covers only about half of the SC vocabulary on most exams.</p>
<p>If your goal is to learn to use the words in your own writing, I <em>love</em> a dictionary called the Advanced Learner's English Dictionary (Collins Cobuild). It's primarily for ESL students but it has most words on most vocab lists, so I recommend it for native speakers as well. The reason I like it so much is because it provides definitions in the form of sentences, not standalone phrases: for instance, while most dictionaries would say something like </p>
<p>"fruition, n. the realization of something that was desired or hoped for"</p>
<p>this dictionary will say something like</p>
<p>"fruition, n. If something comes to fruition, it starts to succeed and produce the results that were intended or hoped for."</p>
<p>These definitions make it much, much easier to use words correctly in your own writing. What's more, the sentences are based on the dictionary maker's analysis of millions and millions of printed words: they reflect important analysis about the way words in English are really used.</p>
<p>But, obviously, if you are trying to learn how to use words correctly as you go, you can't learn nearly as many words. When you're learning words for reading and writing, you're looking at 5-10 a day, tops, I think. When you're learning words for reading and test-taking purposes, you can do as many as 80 a day if you have to (although I don't recommend it). So you have to decide on your objective. </p>
<p>To sum up:</p>
<p>If your only goal is to make yourself a better reader and test taker, or you are taking the test this Nov/Dec, I'd say that you can lean on the Barrons defs and forget the dictionary.</p>
<p>If you are trying to make yourself a better writer and speaker, or you have a year or so to prepare, I'd invest in the Collins COBUILD Advanced Learner's Dictionary ($30) and go more slowly. </p>
<p>In neither case do I think that the American Heritage and Webster's dictionaries is significantly better than the Barrons list, I guess.</p>