What does Si mean?
Si /si/ [1 syll.] as a name for boys. Si's name origin is Hebrew, and Si means "to hear, listen; reputation". Si is an alternate spelling of Simon (Hebrew). Compare last name Sei.
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 the previous year), Szymon, Simpson, Sim and Simeon are the popular varying forms of Si (not in Top 1000) listed in the Top 1000. Usage of these boy names was at its highest during 1880-1889 (usage of 0.4046%) and has become significantly lower since (usage 0.1538%, 62% less), with the versions Simeon and Sim becoming less stylish. Simon (#231) 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)