To stoop or descend; to let one's self down; to submit; to waive the privilege of rank or dignity; to accommodate one's self to an inferior.

do something that one considers to be below one's dignity

debase oneself morally, act in an undignified, unworthy, or dishonorable way; "I won't stoop to reading other people's mail"

behave in a patronizing and condescending manner

To consent.

treat condescendingly