bird flying, high ambition
隺 centers on a bird soaring upward, which extends naturally to the idea of high ambition or aspiring to rise.
隺 is thought to combine 隹 (a short-tailed bird) with 冖 (a cover or something above), suggesting a bird flying upward or rising high. The exact historical development is uncertain.
The top 冖 looks like a high ceiling or the sky, and 隹 is a bird. Picture a bird breaking through the cover and soaring upward with high ambition.
For コク, imagine a bird with high ambition flying toward a distant peak, and a voice calls out 'Cock-a-doodle-doo!' as it rises: Cock -> コク.