An adjective used to describe a significant other when other words simply don't seem to be enough to satisfy. Amterful takes the positive aspects of the words Amazing, Beautiful, Wonderful, and Wicked, then melds them together and raises their status to an even greater complimentary level than held previously. When a boy tells his girl that she is Amterful, it is one of the highest praises he can possibly deliver.
Kwin-See: "Maggie, you are the most amterful girl I have every met. I love you."
Maggie: "Aww, that's so sweet! I love you too. :)"