When Words Suddenly Become Meaningless Sounds
If you repeat a single word over and over, your brain will eventually strip it of all meaning. The word transforms from a symbol for an object into nothing more than a series of strange, repetitive mouth noises.
This phenomenon occurs because your neural pathways become fatigued from constant over-activation. Your brain essentially hits a pause button, forcing you to focus on the mechanical sound rather than the concept behind it. Interestingly, even just staring at a word for a long time can trigger this same glitch in perception. It is a fascinating reminder of how much effort our minds constantly put into turning simple noises into complex thoughts.
Source: Semantic satiation