There are many good online dictionaries available for free from home. Dictionary.com and Merriam-Webster are two good examples of reliable dictionary resources. Another good online dictionary is the Encarta Dictionary. Its best feature is its ability to translate quickly from Spanish, French, Italian, & German into English, or vice-versa.
In addition, you can gain acces to the Oxford English Dictionary through us.
If you are interested in subject dictionaries (like medicine, law, economics, biology) or foreign language, bilingual dictionaries (French, Spanish, German, Italian), then the Oxford Reference Online: Premium Collection is for you.