This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
紭 combines 糸 (thread) with 弘, which likely contributes a sound component. The exact historical development is uncertain.
The left side 糸 suggests thread or netting. The right side 弘 can be seen as a bow 弓 with a hand 厶 pulling it, like stretching a net. Together they hint at a net or rope, but the meaning is unclear.
For コウ, imagine a net made of thread 糸 being stretched wide like a bow 弘, and the sound of the bowstring is a deep 'koh': koh -> コウ.