Dictionary is an application developed by Apple as a part of OS X. The application provides definitions and synonyms from the New Oxford American Dictionary, 3rd Edition and Oxford American Writer's Thesaurus, 2nd Edition. It also includes a section for browsing Wikipedia articles and a section called "Apple" which includes Apple-related items. Some versions of OS X 10.7 and above also ship British and/or Japanese [url removed, login to view] can be entered in the search bar by just typing the first few letters. The application will perform an incremental search to show any matching headwords or forms, and will try to bypass spelling errors. Clicking on any word in a definition searches for that word in the dictionary again. Almost any word is clickable, except the pronunciations in phonetic characters and numerals.
The Preferences allow a user to select from three different pronunciation schemes, either US English (Diacritical or IPA), or British English (IPA).
The dictionary and thesaurus in Dictionary are in an XML format, but make use of precompiled binary index files to access the XML file directly. Therefore, the lexicon cannot easily be modified. However, the user can add new words to the Mac OS X system-wide spell checker, which uses its own lexicon.
In applications which support "Services", there is an option in the application menu (for example, Safari>Services>Look up in Dictionary) which brings up the Dictionary application and displays the definition of a selected word. The same option appears in the contextual menu after a Control-click on the selected word.
The key combination Control Command D can be used in Cocoa applications which display text – it brings up a small contextual menu-like definition or synonym of the word under the cursor.
A three finger tap on the trackpad (either the built-in MacBook trackpad or the Magic Trackpad) is a faster alternative to the Control Command D shortcut.
In applications which support the ability of the user to drag selected text, it is possible to select a word and drop it onto the icon of the Dictionary application in the Dock.
Dashboard includes a widget for accessing the Dictionary application.
Mac OS X catches any queries to the dict:/// URI scheme, say from a web browser, and routes them back to the Dictionary application.
Since OS X Leopard, the dictionary has been integrated with the Spotlight feature.