"kubernan" in ancient greek means to steer
"kubernetes" is helmsman
"gubernare" means to steer or to govern in Latin
"gubernator" is "governor" in Latin
Which then leads into the modern word "Gubernatorial", et al.
(Why the pun? Kubernetes was heavily inspired / guided by Google's internal scheduling tool, which was named Borg (http://blog.kubernetes.io/2015/04/borg-predecessor-to-kubern...).)
comments above are right -- we wanted to stick to the nautical theme that was emerging in containers and 'kubernetes' (or helmsmen is greek) seemed about right. the fact that the word has strong roots in modern control theory was nice also.
fun fact: we actually wanted to call it 'seven' after seven-of-nine (a more attractive borg) but for obvious reasons that didn't work out. :)