reduce, contract, exploit, reproductive organ of infant
脧 centers on reduction or contraction, with a rare anatomical sense referring to an infant's reproductive organ. The meanings do not share one clear conceptual center; the reduction sense and the anatomical sense are distinct.
脧 combines the flesh radical ⺼ with 夋, which likely contributes the sound. The exact historical development is uncertain, and the connection between the reduction sense and the anatomical sense is unclear.
The flesh radical ⺼ suggests a body part, while 夋 looks like a person walking away. Imagine a body part that shrinks or reduces, like an infant's organ, or the idea of contracting flesh.
For サイ, picture a sigh of relief as a swelling reduces: sigh -> サイ, and the flesh radical ⺼ shows the body part contracting.