Fuzzy matching enables you to match similarly spelled words in queries. Oracle Text provides entity extraction for multiple languages.
Stemming enables you to match words with the same linguistic root. For example a query on $speak, expands to search for all documents that contain speak, speaks, spoke, and spoken.
Fuzzy matching and stemming are automatically enabled in your index if Oracle Text supports this feature for your language.
Fuzzy matching is enabled with default parameters for its similarity score lower limit and for its maximum number of expanded terms. At index time you can change these default parameters.
To automatically detect the language of a document and to have the necessary transformations performed, create a stem index by enabling the index_stems attribute of the AUTO_LEXER. The stemmer that corresponds to the document language will be used and the stemmer will always be configured to maximize document recall. Additionally, for documents in languages that use compound words such as German, Finnish, Swedish, and Dutch, if index_stems is set to YES, then compound word stemming will automatically be performed. Compounds are always separated into their components stems.
To improve the performance of stem queries, create a stem index by enabling the index_stems attribute of the BASIC_LEXER.
Oracle Text Reference to learn more about fuzzy matching and stemming