So is the two letter word actually in all your hits? 

Are you only searching for the two letter word? I am not aware of a minimum number of characters except when using a wildcard.

The word or abbreviation is SI. I do see yellow highlight where SI appears by itself, but there are hundreds of thousands of returns where I don't see a highlighted SI, but I do see basic, assist, Asia, etc.

It makes me wonder how well the indexes handle a word like this. Ideally, si should search like any other word, No?

What is the minuimum using a wildcard?

scott 

According to this it is 3, but I am pretty sure that it is only for 32-bit indexes.  What version of EV and DA and do you have any 32 bit indexes?

About the search criteria options

You could enable Search Criteria and see what is being passed to EV.

Discovery Accelerator searches return unexpected results

9.0.3.... 32 bit indexes.

Is this where it says at least 3 characters?

A wildcard search always finds items that match your search criteria and that were archived in Enterprise Vault 10.0 or later. To ensure that the search results also include older matching items that are in your archives, enter at least three other characters before the wildcard. For example, the following search string returns hits for the words "make", "maker", "making", "wonder", "wondering", and so on:

Thanks Tony.... My client was under the impression that they were getting partial hits on SI.. i.e. basic, assist, Asia, etc. Infurther investigation I realized that every e-mail in their search results had a stand alone SI... so it does work with only 2 letters.