We've got a tiny little poem in front of us, so we're going to pay a lot of attention to every word, starting with the title.
The title tells us that this poem is spoken by "Oread." What, pray tell, is an "Oread"? Is it a name? A place? A kind of toothpaste?
An Oread is a thing, actually. It's a type of nymph, specifically a mountain/grotto-dwelling nymph, who prances around the mountainous forest doing nymph-like things, such as being dainty and beautiful. The Oread comes from Greek mythology.
The title, then, tells us who is speaking in the poem. But the poem doesn't name this particular Oread, or give us any specific info about her. It's almost like H.D. has named her poem with a species name, but hasn't told us about the specific member of the species who is talking. Like H.D. has named her poem "Beagle" instead of "Snoopy."
The effect of this curious naming scenario is that the Oread of the poem is generalizable. We get the feeling that she speaks not just for herself, but for all Oreads.
And hey, just in case it hasn't crossed your mind already: beware. For we are in the land of the dramatic monologue. We've got a fictional character (who is most certainly not the poet) speaking to a specific audience. Neat-o.