Semantic search denotes search with meaning, as distinguished from lexical search where the search engine looks for literal matches of the query words or variants of them, without understanding the overall meaning of the query. Semantic search is an approach to information retrieval that seeks to improve search accuracy by understanding the searcher's intent and the contextual meaning of terms as they appear in the searchable dataspace, whether on the Web or within a closed system, to generate more relevant results. Modern semantic search systems use vector embeddings which convert words, phrases, or documents into numerical vectors. This allows the engine to find results based on meaning, not just exact keyword matches.
Source: Wikipedia, CC BY-SA 4.0 — https://en.wikipedia.org/wiki/Semantic_search