Noun september has 1 sense
  1. September, Sep, Sept - the month following August and preceding October
    --1 is a kind of Gregorian calendar month
    --1 is a part of Gregorian calendar, New Style calendar; fall, autumn
    --1 has parts:
     Michaelmas, Michaelmas Day, September 29; Labor Day; Citizenship Day, September 17; American Indian Day; mid-September; autumnal equinox, September equinox, fall equinox; 9/11, 9-11, September 11, Sept. 11, Sep 11