צ \ ץ Tsade, 18th letter, Gematria 90
צ is the last letter of the set of 5 letters that has a different final (end of word) form ץ.
In Modern Hebrew, צ is pronounced as TS in Tsunami, or Cats.
In Aramaic צ is pronounced like an S sound between S and TS. Get your mouth ready to say TS, but vocalize an S instead, keeping your tongue like a rounded cup against the edges of the roof of the mouth. That's צ in Aramaic.
In Hebrew a rightous/holy person is called a צדיק (tsadik). In Aramaic is צדיקא (ṣadiqā). I am guessing TLS calls Rabbi AA a צדיק.