four horses
駟 refers specifically to a team of four horses, typically harnessed together to pull a chariot or carriage.
駟 combines 馬 (horse) with 四 (four), directly representing a team of four horses. This is a straightforward semantic compound.
The left side is a horse 馬, and the right side is the number four 四. Picture four horses lined up together, pulling a single chariot.
For シ, imagine the four horses standing in a row, and you say 'Sheesh, that's a lot of horses!' The 'Shee' sound cues シ.
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