under, underneath, below, down, inferior, bring down
丅 centers on a position or direction that is lower or beneath something else: under, below, or down. The senses of inferiority and bringing down are natural extensions of this spatial idea.
丅 is an ancient form of 下, representing the idea of 'below' by placing a short mark beneath a reference line. The modern form 下 developed from this early pictographic representation.
The long horizontal line is a reference surface, and the short stroke below it marks the position underneath. 丅 is under or below.
For カ, imagine a car parked under a bridge: car -> カ, and the car is below the bridge just as 丅 is below the line.