"The AAT is a structured vocabulary currently containing around 131,000 terms and other information about concepts. Terms for any concept may include the plural form of the term, singular form, natural order, inverted order, spelling variants, scientific and common forms, various forms of speech, and synonyms that have various etymological roots. Among these terms, one is flagged as the preferred term, or descriptor. There may be multiple descriptors reflecting usage in multiple languages. Preferences for individual contributors may differ and are noted.