I have to say my favorite most beautiful word would be.. Glimpse.
I use it all the time.. as in I caught a GLIMPSE of that star,.. I like it because it reminds me kinda like how something special, or mysterious can almost be attained.. and yet unattanable. Something soo fleeting that only a second of time can be spent, and if you blink you just might miss it.
I also like the word Ephemeral.... hehehe as if you didnt know that already