What is the meaning of “not guilty”?

“acquitted: declared not guilty of a specific offense or crime; legally blameless; "he stands acquitted on all charges"; "the jury found him not guilty by reason of insanity"
wordnetweb.princeton.edu/perl/webwn

In the common law tradition, an acquittal formally certifies the innocence of the accused, as far as the criminal law is concerned. This is so even where the prosecution is abandoned nolle prosequi. ...
en.wikipedia.org/wiki/Not_guilty

"Not Guilty" is a song written by George Harrison. It is featured on his 1979 album titled George Harrison and on the The Beatles' Anthology 3 album. ...
en.wikipedia.org/wiki/Not_Guilty_(song)

A formal plea by a defendant of not being culpable for the crime with which the defendant is charged; A verdict or formal finding by the legal system that a defendant is not culpable for the crime with which the defendant was charged; A member of a jury or tribunal supporting acquittal, or a ...
en.wiktionary.org/wiki/not_guilty

A plea made by an accused person to a criminal charge which then requires the prosecution to prove the person's guilt in court. A Not Guilty verdict represents the prosecution's failure to establish the accused's guilt beyond reasonable doubt.
www.cdpp.gov.au/Victims-and-Witnesses/Glossary.aspx

Denies the charge and places the continuing burden of the City or State to prove its case beyond a reasonable doubt.
www.stowmunicourt.com/definitions.htm

A verdict by a judge or jury that a person accused of a crime did not commit it or that not enough evidence exists to prove beyond a reasonable doubt that the accused committed the crime.
www.arnoldsmithlaw.com/Resources/terminology.cfm”"

“Jared Loughner, Ariz. shooting suspect, appears in court; not guilty plea entered

By Sandhya Somashekhar

Washington Post Staff Writer 
Monday, January 24, 2011; 4:46 PM

PHOENIX - The Arizona man accused in the shooting rampage that critically injured Rep. Gabrielle Giffords appeared in federal court Monday on charges of attempted murder, and the court entered a not guilty plea on his behalf.”