sound made get horse move forward
噠 represents a specific vocal sound used to urge a horse forward, essentially an onomatopoeic command.
噠 combines the mouth radical 口 with 達, which likely provides the sound. The character was created to represent the specific oral command for moving a horse.
The mouth 口 on the left and 達 on the right suggest a spoken command that reaches the horse: the sound made to get a horse moving.
For タツ, imagine a rider clicking their tongue twice: 'ta-tsu' to make the horse start moving. The sharp double sound cues タツ.
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