Replacing a word in Dictionary

I have a problem when incorrectly typing the as "teh" which I am very prone to to do.

When I try to correct it, in Apple's Mail (v 6.5 1508), by right clicking (mountain lion) it tells me that the word "teh" exists when right clicking on it, I get the choice to Look Up "Teh" and gives this dictionary explanation for it.

"Teh" is an Internet slang neologism most frequently used as an English article, based on a common typographical error of "the". Teh has subsequently developed grammatical usages distinct from the. It is not common in spoken or written English outside technical or leetspeak circles, but when spoken, it is pronounced /tɛ/ or /tə/.

When I type in TextEdit (v 1.8), the word "teh" is automatically changed to "the" as I have it in the text substitutions in the system preferences.

In Apple's Pages (09 v4.3) when typing "teh", it is underlined in red and right clicking gives me the choice of correcting it.

How can I remove the reference to teh in the dictionary for Apple's Mail?