word-forming element of Greek origin meaning 1. "after, behind; among, between," 2. "changed, altered," 3. "higher, beyond;" from Greek meta (prep.) "in the midst of; in common with; by means of; between; in pursuit or quest of; after, next after, behind," in compounds most often meaning "change" of place, condition, etc. This is from PIE *me- "in the middle" (source also of German mit, Gothic miþ, Old English mið "with, together with, among").
The notion of "changing places with" probably led to the senses of "change of place, order, or nature," which was a principal meaning of the Greek word when used as a prefix (but it also denoted "community, participation; in common with; pursuing").
The third, modern, sense, "higher than, transcending, overarching, dealing with the most fundamental matters of," is due to misinterpretation of metaphysics (q.v.) as "science of that which transcends the physical." This has led to a prodigious erroneous extension in modern usage, with meta- affixed to the names of other sciences and disciplines, especially in the academic jargon of literary criticism: Metalanguage (1936) "a language which supplies terms for the analysis of an 'object' language;" metalinguistics (by 1949); metahistory (1957), metacommunication, etc.
1784, "abstract political science; purely speculative treatment of politics, unrelated to practical matters;" see meta- "transcending, overarching, dealing with the most fundamental matters of" + politics. Based on metaphysics. Related: Metapolitical, which is attested from 1670s in the sense of "outside the realm of politics."
1768, "penitence, spiritual conversion," from Greek metanoia "afterthought, repentance," from metanoein "to change one's mind or purpose," from meta, here indicating "change" (see meta-) + noein "to have mental perception," from noos "mind, thought," which is of uncertain origin.
1833 (Lyell) in the geological sense, "exhibiting change in form or structure," in reference to rock whose form has been changed by heat or pressure, from Greek meta "trans-" (see meta-) + morphē "form," a word of uncertain origin. Earlier (1816) in a theological sense, "characterized by change of form," from metamorphosis + -ic.