What does Si mean?
How popular is Si?
Si is an uncommon first name for males but a very popular last name for all people (#32743 out of 150436, Top 22%). (2000 U.S. Census)
Simon (#231 from current records) and Sim are the popular varying forms of Si (not in Top 1000) listed in the Top 1000. Adoption of these forms of Si was at its highest during 1880-1889 (adoption of 0.722%) and has become significantly reduced since (adoption 0.385%, 46.7% less), with the version Sim becoming less stylish. Simon is the most fashionable name for newborns in this list, with this name going through a rebound in usage. Below is a graphed comparison of the usage of Si and related names. (2014 Birth Statistics)