density
稠 centers on density: things packed closely together, like thick vegetation or a dense crowd. The given meaning 'density' captures this idea of concentrated, abundant presence.
稠 combines 禾 (grain) with 周, which likely contributes the sound and the idea of being all around or thorough, suggesting grain growing thickly.
Grain 禾 all around 周: imagine a field where grain grows so thickly that it surrounds you on all sides, creating a dense, packed scene.
For チュウ, picture a dense field of grain so thick that you can't see through it, and you say 'chew' as you imagine trying to eat your way through: chew -> チュウ.