A root word is the basic building block of a word, providing the core meaning. Synonyms for root word include base word, stem, and lexical base. Base word emphasizes that it is the foundation upon which other words are built. Stem refers to the part of the word that is left when prefixes and suffixes are removed. A lexical base is a more technical term used in linguistics to refer to the form of a word that conveys the basic meaning. Other related terms include root morpheme and morpheme, which are used to describe the smallest unit of meaning in a language.