Bret Devereaux

It's totally untrue. The entire English state dating back to Anglo Saxon kingdoms had these provisions. Same with the Crusader states. They dominate the literature. It can be about anyone connected to the nobili that the "historians" of the period deigned to write about.

You should try to be more careful with language.

You should try to familiarize yourself with the period. Unlike antiquity you can't hide your questionable analysis and conclusions behind the fragmentary nature of the sources.

And you're totally cool with 'milites' covering armed mariners despite the fact that it rarely did in the middle ages?

It means exactly that in some of the Roman sources, which seems relevant to our understanding of the term. Cf. Plaut. Capt. 1.2.61 Angry certainty is almost always unbecoming in a historian.

"Angry certainty" ....yet you're certain that it was used in the way you claim when it's abundantly clear it's not. Which is more probable: unified consistent usage amongst authors who pretended to know more Latin than they did or fragmentation?

In as much as I am staring at the entry in the Lewis & Short which reads "a soldier in sea-service, a marine" yes, I am pretty confident. The thing about a philological question like this is it takes only one example to demonstrate a usage.

The usage in Roman times for sailor was clearly different than what they used for ground pounder or naval infantry. So no unified term then or now. Certainly not by the medieval period.