1570s, "a fact directly observed, a thing that appears or is perceived, an occurrence," especially a regular kind of fact observed on certain kinds of occasions, from Late Latin phænomenon, from Greek phainomenon "that which appears or is seen," noun use of neuter present participle of phainesthai "to appear," passive of phainein "bring to light, cause to appear, show" (from PIE root *bha- (1) "to shine"). Meaning "extraordinary occurrence" is recorded by 1771. In philosophy, "an appearance or immediate object of experience" (1788). The plural is phenomena.

shortened form of phenomenon, U.S. baseball slang, attested by 1890.

1797, "the science of phenomena, as distinct from that of being;" 1840 as "a description or history of phenomena," the latter sense from German Phänomenologie, used as the title of the fourth part of the "Neues Organon" of German physicist Johann Heinrich Lambert (1728-1777), coined from Greek phainomenon (see phenomenon) + -logia (see -logy). Psychological sense, especially in Gestalt theory, is from 1930. Related: Phenomenological; phenomenologically.

1803, "pertaining to or of the nature of a phenomenon," a hybrid from phenomenon + -al (1). Meaning "remarkable, exceptional, exciting wonder" is by 1850.

[Phenomenal] is a metaphysical term with a use of its own. To divert it from this proper use to a job for which it is not needed, by making it do duty for remarkable, extraordinary, or prodigious, is a sin against the English language. [Fowler]

Related: Phenomenally.

*bhā-, Proto-Indo-European root meaning "to shine."

It forms all or part of: aphotic; bandolier; banner; banneret; beacon; beckon; buoy; diaphanous; emphasis; epiphany; fantasia; fantasy; hierophant; pant (v.); -phane; phanero-; phantasm; phantasmagoria; phantom; phase; phene; phenetic; pheno-; phenology; phenomenon; phenyl; photic; photo-; photocopy; photogenic; photograph; photon; photosynthesis; phosphorus; phaeton; sycophant; theophany; tiffany; tryptophan.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit bhati "shines, glitters;" Greek phainein "bring to light, make appear," phantazein "make visible, display;" Old Irish ban "white, light, ray of light."

scientific name for the phenomenon of déjà vu, 1895, Modern Latin, from Greek pro "before" (see pro-) + -mnēsia "memory" (see amnesia).

23rd letter of the Greek alphabet. Its use for "psychic force, paranormal phenomenon" dates from 1942 (probably from psychic (adj.)).

1883, "history of an individual soul; the natural history of the phenomenon of mind," from psycho- + -graphy. Earlier it meant "spirit-writing by the hand of a medium" (1863).