Searching longer keywords first then eventually the shorter once

[nqioweryuadfge]

I am attempting to find a way to search for long keyword tails first before searching for the shorter once in VB.NET. My research on Google never offered a way to search for words like that. This is for my grammar checker database that has numerous amounts of words that should do the replacements in a sequence. If you were to change the shorter once first, then one would not find a way of eliminating the errors that are left by the shorter once.... The shorter once are mainly meant for enhancing the grammar. I have just found a way of eliminating the stackoverflow on my code so that will not be an issue. I only mention this because there are those who are familiar with my code! If one were to offer a solution, would it work on a context menu? I am only mentioning this because, this is the only part that needs restructuring.

checkWord = replacements.Keys.ElementAt(nextCheckIndex)
        foundIndex = RichTextBox1.Find(checkWord, startZ, RichTextBox1.TextLength, RichTextBoxFinds.WholeWord)