For the record, my name is Markos. "Kos" is the second half of my name. (An old Army nickname.)
So, "Kos" rhymes with Markos. Or "morose". "Prose". "Dose".
NOT Kahs. Or "Chaos". Or "Cause".
Now discuss other, more interesting topics. Thanks!
Update: Ok, "prose" and "dose" don't work since they use the phonetic "z" sound. It's "kos" with the "s" sound. Thankfully, the dreadfull depressing "morose" still works.