bind, firm, secure, strong
巩 centers on making something firm and secure by binding or strengthening it. The meanings 'bind', 'firm', 'secure', and 'strong' all flow from this idea of reinforcement.
巩 combines 工 (work, tool) with 凡 (a phonetic element suggesting 'to bind' or 'to hold'). The character likely originated as a depiction of binding or reinforcing with a tool, leading to the meanings of firmness and strength.
The left side 工 looks like a sturdy tool or beam, and the right side 凡 resembles something being wrapped or bound. Picture using a strong tool to bind something tightly, making it firm and secure.
For キョウ, imagine a strong 'kyo' (like the first part of 'kyo-yu' or a firm 'kyo' sound) when you pull the binding tight: kyo -> キョウ, and the binding becomes secure.