WordNet (r) 3.0 (2006):

PSA
    n 1: a protein manufactured exclusively by the prostate gland;
         PSA is produced for the ejaculate where it liquifies the
         semen and allows sperm cells to swim freely; elevated
         levels of PSA in blood serum are associated with benign
         prostatic hyperplasia and prostate cancer [syn: prostate
         specific antigen, PSA]

The Free On-line Dictionary of Computing (19 January 2023):

PSA

   Problem Statement Analizer.  See PSL/PSA.