wagtail
鴒 refers specifically to the wagtail, a small bird known for its characteristic tail-wagging behavior.
鴒 combines 令 (likely a phonetic component) with 鳥 (bird), forming a character for a specific bird species. The exact historical development is uncertain, but the structure is a typical phono-semantic compound.
The left side 令 looks like a person giving an order, and the right side 鳥 is a bird. Imagine a bird that wags its tail as if giving commands—a wagtail.
For レイ, picture a wagtail laying eggs in a nest: lay -> レイ, and the bird's tail wags as it settles down.
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