1. What do these two words have in common?

CHAMELEON
BOUNDARIES

2. What do the following words or letter pairs have in common?

IN
IT
RI
MU
UM
AD

Answers:

1. Each word contains one of the twelve signs of the Zodiac:

chamdLEOn
boundARIES

2. Each word can be either preceded, followed, or both by CH:

CHIN / INCH
CHIT / ITCH
RICH
MUCH
CHUM
CHAD