blow, command
咐 centers on directing air or words outward: blowing breath or issuing a command. Both meanings share the idea of forceful oral expression.
咐 combines 口 (mouth) with 付, which likely contributes the sound and the idea of attaching or applying. The character expresses directing breath or speech from the mouth.
A mouth 口 attached 付 to a command: imagine a general's mouth issuing a sharp blow of air as he shouts an order.
For フ, picture a commander blowing a whistle and shouting 'Foo!' to give a command: Foo -> フ.
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