phenomenon

A thing or being, event or process, perceptible through senses; or a fact or occurrence thereof.

The year 1866 was signalised by a remarkable incident, a mysterious and inexplicable phenomenon, which doubtless no one has yet forgotten.

The Indians, making a hasty inference from a trivial phenomenon, arrived unawares at a probably correct conclusion.

A knowable thing or event (e.g. by inference, especially in science).

An electromagnetic phenomenon.

A kind or type of phenomenon (sense 1 or 2).

A volcanic eruption is an impressive phenomenon.

Appearance; a perceptible aspect of something that is mutable.

I verily believe that in the Moon there are no rains, for if Clouds should gather in any part thereof, as they do about the Earth, they would thereupon hide from our sight some of those things, which we with the Telescope behold in the Moon, and in a word, would some way or other change its Phœnomenon.

A fact or event considered very unusual, curious, or astonishing by those who witness it.

The phenomenon of a huge blazing fire, upon the opposite bank of the glen, again presented itself to the eye of the watchman. . . . He resolved to examine more nearly the object of his wonder.

Not much later—perhaps only two or three weeks later he has discovered meaning in them; he knows that they say "The cat sat on the hat." How this happens no one really knows, despite the efforts of philosophers and psychologists over two and a half millennia to study the phenomenon. [...] Indeed, this discovery of meaning in symbols may be the most astounding intellectual feat that any human being ever performs—and most humans perform it before they are seven years old!