phenomenal

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of, relating to, or constituting phenomena or a phenomenon.
• adjective Extraordinary; outstanding.
• adjective Philosophy Known or derived through the senses rather than through the mind.

from The Century Dictionary.

• Of, pertaining to, or of the nature of phenomena, or the appearances of things, as distinguished from the things in themselves; pertaining to the occurrences or changing phases of matter or mind.
• Of the nature of a phenomenon, or extraordinary fact in nature; so surprising or extraordinary as to arrest the attention or excite wonder; impressively notable or important; beyond what is common or usual; remarkable: as, the phenomenal growth of the United States; a brain of phenomenal size.
• noun That which is in the nature of a phenomenon.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Relating to, or of the nature of, a phenomenon; hence, extraordinary; wonderful.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective colloquial Very remarkable; highly extraordinary; amazing.
• adjective sciences Perceptible by the senses through immediate experience.
• adjective philosophy Of or pertaining to the appearance of the world, as opposed to the ultimate nature of the world as it is in itself.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective exceedingly or unbelievably great
• adjective of or relating to a phenomenon