Latent semantic indexing (LSI) is a technique used to index and retrieve documents based on the similarity of the words in the document, not just the literal match of the terms. Semantic search is similar to LSI in that it understands the meaning of the words in a document, not just the literal match of the terms. However, semantic search goes one step further by also understanding the relationship between the words in a document, not just their similarity. This means that semantic search can offer more relevant and accurate results than LSI.