1. What do the following words have in common?

RED
BLACK
GREEN
WHITE
YELLOW

2. What do the following words have in common?

MAYOR
OCTET
AUGMENT
MARINATE
JANITOR

Answers:

1. Each word can be followed by LIGHT.

2.   The first three letters of each word are the name or abbreviations of months of the year.

(Credit: Chicago Tribune Crossword
Josiah Breward - ABBREVIATED CALENDAR)