_Lexical search_, or keyword-based retrieval, as opposed to [[Semantic Search]], is a type of search where a query is compared against a collection of text documents by directly matching the words in the query. These can also be referred to as "lexical filters". E.g., "Apply lexical filters before semantic ranking." See [[Two Tower Embeddings ("Learned Embeddings")]] when lexical filters get out of hand and slow down search. ex. [[Okapi BM25]] However, lexical search isn't just about the BM25, but building phrase search in a way that respects the graph-based nature of the token stream. The lexical search element of a [[Information Retrieval (IR) System]] System might be generated by an LLM. AND OR statements.