This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 谹 is uncertain. It visually combines 谷 (valley) and 厷, but the original semantic and phonetic roles are unclear.
With no clear meaning, picture a deep valley (谷) stretching wide (厷 suggests a broad shape), hinting at something profound or vast.
For コウ, imagine a deep valley echoing with a low, resonant sound: 'kohhh' — the sound cues コウ.