A History of Short Words

From the New York Times Crossword Puzzle

OCT

Mon, 15 Nov '21
Mo. for trick-or-treaters
Thu, 26 Aug '21
Bat Appreciation Month, appropriately: Abbr.
Sun, 4 Jul '21
What "10" might mean: Abbr.
Wed, 10 Feb '21
Mo. with a holiday on its final day