a missing "fast"?

[Laurence Horn]

Just saw a production of "Measure for Measure" in the park here last night and was struck by a use of _fast_ that doesn't seem to correspond to any of the entries under the adverbial FAST in the OED.  The speaker, Claudio, has just been condemned to death by Angelo, the puritanical fill-in chief of state in Vienna, for fornication, as revealed by…well, you'll see:

CLAUDIO:
Thus stands it with me: upon a true contract
I got possession of Julietta's bed:
You know the lady; she is fast my wife,
Save that we do the denunciation lack
Of outward order: this we came not to,
Only for propagation of a dower
Remaining in the coffer of her friends,
From whom we thought it meet to hide our love
Till time had made them for us. But it chances
The stealth of our most mutual entertainment
With character too gross is writ on Juliet.

So they were affianced or common-law-married partners who would have been actually married except without the official banns being posted.  As far as I can tell, when Claudio says "she is fast my wife" in the third line, he means that Juliet is almost, nearly, or virtually his wife.  But as noted, this isn't in the OED entry for FAST, adv.  What's striking is that this is precisely the main (or only?) sense of the German word _fast_.  Is this just a coincidence, or did that sense persist into Early Modern English as well, in which case why no subentry for it along with those for 'fixedly', 'diligently', 'vigorously', 'securely', 'strictly', 'rapidly', 'immediately', and 'in a dissipated manner'?  Or is Claudio's use somehow an instance of 'securely' (with the "save" clause marking the way in which the bond isn't all that secure)?  None of the relevant cites at that subentry really seem at all parallel.  

LH
	
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