to stumble and fall prone stiff in death
踣 centers on a sudden, fatal collapse: stumbling forward and falling prone, stiff in death. The meaning is narrow and dramatic, describing a specific kind of lethal fall.
踣 combines 足 (foot) with 咅, which likely contributes the sound. The character expresses a fatal stumble or fall related to the foot.
The left side is 足 (foot), and the right side 咅 looks like a person standing stiffly. Picture a foot tripping, causing the body to fall forward and land prone, stiff as a board.
For ホク, imagine a person stumbling and falling with a heavy, hollow thud: the sound 'hoku' echoes the dull impact of a body hitting the ground stiffly.