Lemmatisation is a crucial technique in Natural Language Processing for text normalization and pre-processing. It refers to the process of identifying the root word of a given word in a sentence. However, "lemmatization" has synonyms that can be used interchangeably. Such synonyms include lemmatizing, stemmatization, stemming, and normalization. Stemming is a similar process of reducing a word to its root form, although it is more aggressive and may yield alternative or incorrect forms. Normalization, on the other hand, involves converting text to a uniform format or standard. Therefore, lemmatisation and its synonyms help in improving the accuracy of text analysis and making sense of the large volumes of data processed by machine learning algorithms.