The phrase "on one's knees" is often used to describe a position of humility, submission, or begging. However, there are several synonyms that can be used to convey the same meaning in different contexts. "Bowing down," for example, can suggest reverence or appreciation, while "prostrate" implies total submission or defeat. "Kowtowing" comes from a kneeling gesture in Chinese culture that signifies respect, while "groveling" connotes a sense of desperation or subservience. Other options include "surrendering," "yielding," and "subordinating oneself." Overall, the choice of synonym will depend on the intended emphasis and tone of the sentence.