ruminate

This term describes a slow, cyclical process of mental digestion. It suggests a state of preoccupation where a person turns a thought over and over in their mind, often with a sense of obsession or anxiety. While pondering is generally neutral or curious, ruminating often carries a heavier, more brooding connotation, implying that the thinker is stuck in a loop of reflection.

In a biological sense, the word refers to the physical act of chewing cud. This literal process of regurgitating and re-processing food serves as the direct ancestor to the metaphorical meaning of re-processing an idea. The transition from the stomach to the mind highlights the repetitive nature of both actions.