Something often missing from vocabulary tests -- and arguably more impressive than raw, crystallized vocab -- is the ability to deduce the meaning of new words

Something often missing from vocabulary tests -- and arguably more impressive than raw, crystallized vocab -- is the ability to deduce the meaning of new words on the fly, whether from context or absent any context (in which case, the meaning is ascertained from roots, prefixes, suffixes, etc.). I'd love to see a test of this skill. For instance, I doubt many people encounter the word "reck" in their daily lives. But I'd give props to someone whose brain would quickly draw the connection to the more frequently seen "reckless," thereby deducing that the word had something to do with caution or concern. Similarly, your point has some validity. Most of the time, we don't acquire language through reading the dictionary; we acquire it primarily through context in the course of reading or conversation. This is why, when pressed to define words, we'll often reach for a string of synonyms, or else provide usage in sample sentences. I bet few people here, let alone anywhere, could render dictionary-acceptable definitions of 99% of the words they know. (On the flipside, this is also why we forget most of the words we crammed in preparation for the SAT back in the day; we learned them completely out of context and in an artificial way).