Two companies recently pitched me on their semantic engines. These are not search engines, which is what most people think. Rather, they are databases and algorithms that hold the structure of language (in both cases, the English language). At the most basic level semantic engines tell you what's synonymous with what. At the advanced end of the spectrum they know how grammatically similar phrases like "take a seat," "take a stand," and "take a lollipop," mean completely different things.