lexeme

In linguistics, a lexeme is the basic meaning ascribed to a word regardless of the number of inflectional endings it may have. Lexemes are often referred to as being abstract units of lexical meaning. A lexeme can be thought of as the core idea or meaning that all of the forms of a single word can take.

For example, walk, walking, walked, walks, are different forms of the same lexeme. One word is chosen to be the canonical, or default, representation of the lexeme. This form is called the lemma. The lemma for this example lexeme is walk.