: : : "Host" is a word often found in Biblical translations from the KJV era onward, but it's not often used much any more (except maybe in Tolkien-inspired fantasy literature). It comes from Middle Latin, so I don't know if the root word was used in the Vulgate. It generally is used to mean "an army" or "a multitude". I've never seen any source which tried to assign a range of numbers to it.

: : Interestingly the Latin root of host, hostis, was the progenitor of two words in modern English of very different meanings. Host as in the person looking after guests, and hostile. I believe the basic original term meant "stranger." This was then extended to one who gave protection to strangers in a host-guest relationship. At the same time the strangers which a small community came into contact with were often both hostile and in armed bands or armies and so the use of host in that sense developed.

: : An Anglo-Saxon definition of "army" which might equate with host, was an armed band numbering 200 and over.

: I`m not at all an expert, but I think the Greek equivalent of the Lord of Hosts, used in the septuagint and liturgical Greek, is o kyrios ton dynameon (I can`t get Greek letters here, but it`s the origin of our dynamic/dynamism) and I always understood lord of hosts as lord of powers, of the strong, of forces.

I know St Michael is described in Greek Orthodox usage as "Arch-strategos of the Heavenly Host" that is "General-in-command of the forces of Heaven", but I can't recall what the original Greek term for "Host" was in this context. I guess there is quite a lot of leeway in translation.