Latent semantic indexing, other wise known as LSI, is not what is it is frequently claimed to be. It is not something that a webpage can be optimized for, so that it conforms to LSI standards. There is no such thing as LSI standards. In fact, latent semantic indexing cannot be described to a layman in simple terms. LSI cannot be used to improve your search engine listings since it is nothing more than a concept. A very mathematically complex concept, sure, but a concept nevertheless, and concepts cannot be used for tangible results. However, there is a guide to what Google are trying to achieve in the use of the words within the term. In the context in which it used, the word semantics here means the meaning of words, and specifically the meaning to which words are put, and what is being conveyed, in the way that the term is used.