What Does Resplendent Mean?

The word resplendent is used as an adjective and most of the times you will find that the word is being used in association with 'in something' and the meaning the combined term conveys is that of something that is brightly coloured in a very impressive way. But the word is not being used in day-to-day conversation and usually it is used when the writing is of formal kind or of literary type. The sentence that can make you understand the word well is following: John looked at Nina, resplendent in her red dress. The above mentioned sentence says that when John looked at Nina, he just could not move his sight as she was looking so impressive.
      
The adverb that can be formed out of the adjective is resplendently but there does not exist any verb or noun form of the word.