What term refers to being abjectly submissive or slavish?

The term that refers to being abjectly submissive or slavish is "servile." This word is often used to describe a person who is excessively willing to serve others, showing an attitude that suggests a lack of self-respect or an eagerness to please, often at the expense of their own dignity. It conveys a sense of following or complying in a way that lacks strength and independence, embodying a form of subservience.

In contrast, the other terms do not align with this meaning. "Shrewd" pertains to being astute or having sharp judgment, particularly in practical matters. "Squalid" describes something that is extremely dirty or unpleasant, often due to poverty or neglect. "Revere" indicates a deep respect or admiration for someone or something, highlighting a sense of honor rather than subservience. Thus, "servile" is the most fitting choice to convey the essence of abject submissiveness.