minced meat, cut meat into piece
胾 centers on meat that has been cut into small pieces: minced meat or the action of cutting meat into pieces.
The exact historical development of 胾 is uncertain. It visually contains 肉 (meat) inside a structure that may relate to cutting or dividing, but the component origins are not clearly established.
The character encloses 肉 (meat) within a shape that suggests cutting or dividing. Picture meat being chopped into small pieces inside a container.
For シ, imagine a chef saying 'shh' as they quietly mince the meat: shh -> シ, and the meat is cut into fine pieces.