What do the following words have in common?

SEPARATE
JUNIOR
OCTET
FEBRILE
MAYFLY
JANITOR
MARINADE
DECLARATION
JULIENNE
APRICOT
AUGMENT
NOVELLA

(BIG) HINT:
It has to do with the first three letters of each word.

Answer:

Each word begins with the three letter abbreviation (or name) of a calendar month.

Credit: Josiah Breward
ABBREVIATED CALENDAR