How to access the OS-Language dictionary the PC.

I want to build a word checker application but how to access the vocabulary of the Computer OS is a problem. Show me how to continue from hear please.

string[] wordCollection = new string[]{ ...... };

foreach (string word in wordCollection )
 {
   if(word.Equal(???))
     {
        .......
        .......
     }
    else
     {
       .....
       .....
     }
 }