Etymology
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be- 

word-forming element of verbs and nouns from verbs, with a wide range of meaning: "about, around; thoroughly, completely; to make, cause, seem; to provide with; at, on, to, for;" from Old English be- "about, around, on all sides" (the unstressed form of bi "by;" see by (prep.)). The form has remained by- in stressed positions and in some more modern formations (bylaw, bygones, bystander).

The Old English prefix also was used to make transitive verbs and as a privative prefix (as in behead). The sense "on all sides, all about" naturally grew to include intensive uses (as in bespatter "spatter about," therefore "spatter very much," besprinkle, etc.). Be- also can be causative, or have just about any sense required. The prefix was productive 16c.-17c. in forming useful words, many of which have not survived, such as bethwack "to thrash soundly" (1550s) and betongue "to assail in speech, to scold" (1630s).

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extro- 
word-forming element meaning "outwards," a variant of extra- by influence of intro-.
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radio- 
word-forming element meaning 1. "ray, ray-like" (see radius); 2. "radial, radially" (see radial (adj.)); 3. "by means of radiant energy" (see radiate (v.)); 4. "radioactive" (see radioactive); 5. "by radio" (see radio (n.)).
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post- 
word-forming element meaning "after," from Latin post "behind, after, afterward," from *pos-ti (source also of Arcadian pos, Doric poti "toward, to, near, close by;" Old Church Slavonic po "behind, after," pozdu "late;" Lithuanian pas "at, by"), from PIE *apo- (source also of Greek apo "from," Latin ab "away from" see apo-).
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eo- 

word-forming element, used from mid-19c. (first in Eocene) in compound words formed by earth-scientists, and meaning "characterized by the earliest appearance of," from Greek ēōs "dawn, morning, daybreak," also the name of the goddess of the morning, from PIE root *aus- (1) "to shine," especially of the dawn. Piltdown Man, before exposed as a fraud, was known as Eoanthropus.

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pogon- 

word-forming element from Greek pōgōn "the beard," which is of unexplained origin. Used in Pogonophile (by 1961); pogonophobia (1852).

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an- (1)

privative prefix, from Greek an-, "not, without" (from PIE root *ne- "not"). The Greek prefix is a fuller form of the one represented in English by a- (3).

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quinque- 

before vowels quinqu-, word-forming element from classical Latin meaning "five, consisting of or having five," from Latin quinque "five" (by assimilation from PIE root *penkwe- "five").

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audio- 
word-forming element meaning "sound, hearing," from combining form of Latin audire "to hear" (from PIE root *au- "to perceive"); used in English word formation by 1890s.
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coeno- 

before vowels coen-, word-forming element meaning "common," from Latinized form of Greek koinos "common, public, shared, general, ordinary," from PIE *kom "beside, near, by, with" (see com-).

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