obstruction of breath (qi) as it seeks release, variant of other characters
丂 is a rare character with no clear standalone meaning in modern Japanese. It is described as representing an obstruction of breath seeking release, and it often appears as a variant component in other characters rather than as an independent word.
The exact historical origin of 丂 is uncertain. It is an ancient character that may have depicted something obstructing the breath, but its development is not well documented.
The shape looks like a breath caught in the throat: the top horizontal line blocks the curved stroke below, like air trying to escape but hitting an obstruction.
For コウ, imagine a person coughing as their breath is obstructed: the cough sound cues コウ, and the blocked breath matches the meaning.