Answer:
Look for the definition in dictionary and then re-read the poem.
Step-by-step explanation:
Antiquated words are those words that are outdated or those that are no longer used such as thou, thee, and thine are the outdated words.
In the poem, "A Birthday" by Christina Rossetti, the poet has used certain antiquated words as listed in the question.
The word "halcyon" is an outdated word used to refer to 'kingfisher.' The word 'vair' is used to refer to 'squirrel's fur that is expensive.' And, the word 'dais' is used for 'throne.'
The meaning of the poem can be made by looking for these antiquated words in the dictionary and re-read the text to understand it.