The Noda BiYehuda has a commentary on Shas known as Tzlach - can someone help me by explaining what that stands for?
In his introduction, the Noda Biyehudah says that indeed the sefer was named for his mother (as Shalom mentioned in his comment). He also adds that the ל in לנפש represents his father (since יהודה equals 30, same as ל), and that the word ציון is for his own name, since it has the same gematria as יחזקאל.
The abbreviation also has the connotation of "success" (צלח is the imperative form of הצלחה.) I'm not sure whether that meaning was intended, though.