How/when does one use “a most”?

Question

I've recently come across a novel called A most wanted man, after which being curious I found a TV episode called A most unusual camera.

Could someone shed some light on how to use "a most" and whether it has anything to do with "the most"?

Answer 1

"Most" in this context means "very." As in "a very wanted man." It functions as a "superlative."

Answer 2

This is a special kind of absolute superlative. The OED gives as its sense 2 of most adv. the following:

As an intensive superlative qualifying adjs. and advs.: In the greatest possible degree.
_{For the ceremonial titles, Most Christian, Most Honourable, Most Noble, Most Reverend, etc., see those adjs.}

I don’t think it gets used all that very much anymore. One of the examples is:

1710 Hearne Collect. (O.H.S.) II. 351 ― A most vile, stinking Whigg.