meat
胏 is a rare kanji whose core meaning is simply meat. It has no widely recognized extended senses beyond this basic idea.
胏 combines the flesh radical ⺼ with a phonetic component that is now obscure. The exact historical development of the right side is uncertain.
The left side ⺼ is the flesh radical, often used in body-part kanji. Picture a slab of meat hanging from a hook: the right side looks like a hook and lines of hanging meat.
For シ, imagine a piece of meat sizzling in a pan: the hissing sound 'shhh' cues シ, and the meat is cooking.