In linguistics, an abstract unit of lexical meaning underlying a family of inflected word forms and functioning as a single entry in the mental or written lexicon.

The lexeme 'run' encompasses the forms 'runs', 'ran', and 'running'.

In computer science, a contiguous sequence of characters in source code recognised as a single token during lexical analysis.

During tokenisation, the sequence '==' is identified as one lexeme representing the equality operator.