Parsing "Vale, o valde decóra" in the Ave Regina Caelorum

Question

Ave, Regína cælórum,
Ave, Dómina Angelórum:
Salve radix, salve porta,
Ex qua mundo lux est orta:
Gaude, Virgo gloriósa,
Super omnes speciósa,
Vale, o valde decóra,
Et pro nobis Christum exóra.

I am having trouble deciphering the bolded line of this hymn, especially the word decora. Is it an noun, adjective, or verb? The o makes me think it is either a noun or an adjective acting as a substantative, but then what is the adverb valde doing here?

Answer 1

A valid translation of the relevant piece would be:

O most (lit. very) beautiful [Lady]!

• Decora is an adjective, feminine in gender (see meaning II for the beautiful sense).
• Valde is an intensity adverb making decora an augmentative (i.e., very beautiful). The relevant part of the definition is:
• Not sure about the punctuation, but the noun is either virgo, or just elided. Anyway the context makes it reasonably obvious who we're talking about

Answer 2

Decorus is an adjective that means, in this context, "decorated, ornamented, adorned; elegant, fine, beautiful, handsome." In this case, it is substantivized, "beautiful one."

Valde is the adverb form of validus ("strong") and can be used with a verb, adjective, or adverb to intensify it. It's essentially a glorified way of saying "very."

The whole bolded part can thus be translated:

Farewell, o most beautiful one.