A History of Short Words

From the New York Times Crossword Puzzle

RHO

Sun, 14 Nov '21
Sorority letter
Sun, 19 Sep '21
Letter two before tau
Wed, 1 Sep '21
Letter after pi
Tue, 1 Jun '21
Letter after pi
Sun, 30 May '21
Fraternity letter
Sat, 8 May '21
Sorority letter
Tue, 13 Apr '21
Greek letter that looks like a "P"
Fri, 2 Apr '21
Letter seen in a Christogram