Lemmatization is a process of reducing inflected (or sometimes derived) words to their base form, or root, by taking account of the variants of a word, such as different tenses or plurals. This is usually done by identifying the root of a word and then assigning all words with the same root to a common lemma, or dictionary entry.
It is an important step in many natural language processing (NLP) tasks, such as part-of-speech tagging, parsing and information retrieval. Lemmatization helps to bring together different forms of a word when processing large amounts of text. For example, the words “compute,” “computed” and “computing” all have the same root, so a lemmatizer might map each one to a single lemma.
In linguistics, lemmatization is often used in conjunction with stemmers, which usually do a less sophisticated job of reducing words to their root. Stemmers often remove suffixes of words indiscriminately, while lemmatization combines different forms of a word using heuristics that focus on the individual characteristics of each word.
Lemmatization has many practical applications in language processing tasks, expanding the capabilities of search engines and improving the accuracy of other NLP operations. By accurately lemmatizing data sets, natural language processing software can then apply more sophisticated models that require consistent word forms as input.
The process of lemmatizing words is context-dependent and can vary depending on language and the particular NLP tasks being used. Therefore, it’s important to ensure the proper methods are being used for a given language and task. Many software packages are available for lemmatizing text in a variety of languages, ranging from simple algorithms to advanced machine learning models.
