Phenomenon

n. event or circumstance that can be observed; something unusual; something detected by the senses

A phenomenon (Greek: φαινόμενoν, pl. phenomena φαινόμενα) is any occurrence that is observable.
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Noun
1. any state or process known through the senses rather than by intuition or reasoning
(hyponym) natural phenomenon
2. a remarkable development
(hypernym) development

(n.)
That which strikes one as strange, unusual, or unaccountable; an extraordinary or very remarkable person, thing, or occurrence; as, a musical phenomenon.
  

(n.)
An appearance; anything visible; whatever, in matter or spirit, is apparent to, or is apprehended by, observation; as, the phenomena of heat, light, or electricity; phenomena of imagination or memory.
  

anything that can be perceived as an occurrence or fact by the mind or senses.