phe·nom·e·non 
(fĭ-nŏmə-nŏn′, -nən)
(fĭ-nŏmə-nŏn′, -nən)n. pl. phe·nom·e·na (-nə)
1. An occurrence, circumstance, or fact that is perceptible by the senses.
2. pl. phe·nom·e·nons
a. An unusual, significant, or unaccountable fact or occurrence; a marvel.
b. A remarkable or outstanding person; a paragon. See Synonyms at wonder.
3. Philosophy In the philosophy of Kant, an object as it is perceived by the senses, as opposed to a noumenon.
4. Physics An observable event.
[Late Latin phaenomenon, from Greek phainomenon, from neuter present participle of phainesthai, to appear; see bhā-1 in the Appendix of Indo-European roots.]
Usage Note: Phenomenon is the only acceptable singular form of this noun; phenomena is the usual plural. Phenomenons may also be used as the plural in nonscientific writing when the meaning is "extraordinary things, occurrences, or persons": They were phenomenons in the history of music.