http://www.jurisdictionary.com/dictionary/dictionary a.htm
Ad Litem
Literally, "for the suit". For the purpose of the pending litigation.
Occasionally courts will appoint an attorney to represent a party who cannot represent itself, e.g., an unborn child or a defaulted debtor who left town owing money on his mortgage. Such an attorney is called an attorney ad litem (properly italicized). If a guardian is appointed by the court to stand in the shoes of an incapacitated person or minor, that guardian is called a guardian ad litem, indicating that the guardian is only serving for the purpose of the present litigation
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