pig, large hog
豨 centers on a pig, specifically a large hog. The meanings are straightforward and refer to the animal itself.
豨 combines 豕 (pig) with 希, which likely contributes the sound. The character is a phono-semantic compound where the meaning is carried by the pig radical and the reading by 希.
The left side 豕 is a pig, and the right side 希 looks like a net or trap. Imagine a large hog caught in a net: 豨 is a big pig.
For キ, picture a large hog wearing a key-shaped collar: key -> キ, and the key identifies this particular pig.
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