| 2026-05-22 | Symbol used in summation |
| 2026-01-06 | Letter between rho and tau |
| 2025-10-10 | Greek letter that refers to a lone wolf, in Gen-Z slang |
| 2025-02-10 | Summation symbol, in math |
| 2025-01-21 | Greek letter that represents summation |
| 2023-05-01 | Greek "S" |
| 2023-03-25 | It's at the end of "Oedipus" |
| 2021-08-28 | Symbol for stock volatility, in finance |
| 2021-03-15 | Letter after rho |
| 2020-02-10 | Letter before tau |
| 2019-01-31 | Summation symbol, in math |
| 2018-12-26 | Rho follower |
| 2018-03-15 | Arithmetic series symbol |
| 2016-05-26 | Letter before 7-Down |
| 2015-06-14 | Standard deviation symbol |
| 2015-03-01 | With 65-Down, 160-year-old fraternity founded at Miami University of Ohio |
| 2014-10-21 | Rho-tau linkup |
| 2014-01-11 | Sum symbol |
| 2013-02-17 | Summation symbol in math |
| 2012-04-17 | Summation symbol in math |
| 2012-04-02 | Greek "S" |
| 2012-01-22 | Head of ancient Sparta? |
| 2011-06-21 | Summation signifier, in math |
| 2009-11-19 | Symbol in a Riemann sum |
| 2009-09-29 | Summation symbol |
| 2009-03-15 | Arithmetic series symbol |
| 2006-11-04 | Standard deviation symbol |
| 2005-12-06 | Calculus symbol |
| 2004-02-15 | Standard deviation symbol |
| 2004-01-03 | Standard deviation symbol |
| 2002-08-18 | ___ Society (super-high I.Q. group) |
| 2002-07-24 | Science society ___ Xi |
| 2001-09-30 | Symbol of conductivity |
| 2001-07-15 | Standard deviation symbol |
| 2000-12-02 | Fraternity letter |
| 1999-06-15 | ___ Alpha Epsilon fraternity |
| 1999-03-23 | Greek S |
| 1997-04-28 | Greek letter |