There are a number of online translation services that you can use to translate words, phrases, or even entire bodies of text into another language; however, if you need to do so in OS X then there is a quick way to do so by using the Dictionary utility.
The Dictionary is Apple’s built-in word look-up tool that offers word definitions and thesaurus capabilities, along with access to Apple knowledgebase documentation and Wikipedia articles. It is the tool that the system uses when you right-click a word and choose the option to look it up.
While this tool generally is used for looking up definitions and similar words in the current system language, the dictionary does support a few languages for which it will display information about a selected word in another language. This is not the intended use of the Dictionary, so it is a somewhat crude and limited approach; however, it will give you a number of translated words, and being a contextual option makes it rather convenient.
Translation is available for Spanish, Japanese, Chinese (simplified), and Korean, and can be enabled in the Dictionary app’s preferences:
- Open the Dictionary App.
- Go to the program’s preferences.
- Check one of the four available “Language-English” options that is relevant for you (also the new installed Deutsch-Englisch).
- Optionally re-order the checked entries (this is the order that they will appear in the contextual panel).
When done, close the Dictionary and then three-finger tap a word in a program like Safari, Pages, or TextEdit, or right-click the word and choose the Look Up option. Then you should see it translated into the selected language somewhere in the panel that appears. This should work both ways, so words in English should appear in the non-English language, and vice versa.