To abase something or someone is to humiliate them — no, more than just humiliate them. If you abase another person you are bringing them low, humbling them in a mean, base manner. Not nice at all.
Abase means to bring someone down, often either in their job or their self-esteem. The early Latin bassus, which meant "thick, low," evolved into the Old French abaissier, meaning "to make lower in value or status." The important clue to the word is "base." Consider that the base of anything is the bottom, and you get an idea as to the meaning of the word abase, which means to make someone feel low.