What is Acquittal?

Legal Definition
In the common law tradition, an acquittal formally certifies that the accused is free from the charge of an offense, as far as the criminal law is concerned. This is so even where the prosecution is abandoned nolle prosequi. The finality of an acquittal is dependent on the jurisdiction. In some countries, such as the United States, under the rules of double jeopardy and autrefois acquit, an acquittal operates to bar the retrial of the accused for the same offense, even if new evidence surfaces that further implicates the accused. The effect of an acquittal on criminal proceedings is the same whether it results from a jury verdict, or whether it results from the operation of some other rule that discharges the accused. In other countries, the prosecuting authority may appeal an acquittal similar to how a defendant may appeal a conviction.
-- Wikipedia
Legal Definition
At the end of a criminal trial, a finding by a judge or jury that a defendant is not guilty. An acquittal signifies that a prosecutor failed to prove his or her case beyond a reasonable doubt, not that a defendant is innocent. Thus, a person may be acquitted of a crime but found civilly liable in a civil case regarding that same crime, e.g. O.J. Simpson, because civil cases have a lower burden of proof than criminal cases.
See also
Legal Definition
Contracts. A release or discharge from an obligation or eng agement. According to Lord Coke there are three kinds of acquittal, namely; 1, By deed, when the party releases the obligation; 2, By prescription; 3, By tenure.Co. Lit. 100, a.
-- Bouviers Law Dictionary
Legal Definition
Crim. law practice. The absolution of a party charged with a crime or misdemeanor.

2. Technically speaking, acquittal is – the absolution of a party accused on a trial before a traverse jury. 1 N. & M. 36; 3 M'Cord, 461.

3. Acquittals are of two kinds, in fact and in law. The former takes place when the jury upon trial finds a verdict of not guilty; the latter when a man is charged merely as an accessary, and the principal has been acquitted. 2 Inst. 384. An acquittal is a bar to any future prosecution for the offence alleged in the first indictment.
-- Bouviers Law Dictionary
Legal Definition
In contracts. A release, absolution or discharge from an obligation, liability or engagement. In criminal practice. The legal and formal certification of the innocence of a person who has been charged with crime; a deliverance or setting free a person from a charge of gulit In a narrow sense, it is the absolution of a party accused on a trini before a traverse jury. Thomas v. De Graffenreid, 2 Nott & MeC. (S. Ct) 143; Teague v. Wiiks, 3 McCord (S. C.) 46L Properly speaking, however, one is not acquitted by the jury but by the judgment of the court. Burgess v. Boetefeur, 7 Man. & G. 481, 504; People v. Lyman, 53 App. Div. 470, 65 N. Y. Supp. 1062. And he may be legally acquitted by a judgment rendered otherwise than in pursuance of a verdict, as where he is discharged by a magistrate because of the insufficiency of the evidence, or the indictment is dismissed by the court or a nol. pros, entered. Junction City v. Keeffe, 40 Kan. 275, 19 Pac. 735; People v. Lyman, 53 App. Div. 470, 65 N. Y. Supp. 1062; Lee v. State, 26 Ark. 260, 7 Am. Rep. 611; Morgan County v. Johnson, 81 Ind. 463. But compare Wilson v. Com., 3 Bush (Ky.) 105; State v. Champeau, 52 Vt. 813, 315, 36 Am. Rep. 754. Acquittals in fact are those which take place when the jury, upon trial, finds a verdict of not guilty. Acquittals in law are those which take place by mere operation of law; as where a man bas been charged merely as an accessary, and the principal has been acquitted. 2 Co. Inst. 364. In feudal law. The obligation on the part of a mesne lord to protect his tenant from any claims, entries, or molestations by lords paramount arising out of the services due to them by the mesne lord. See Co. Litt. 100a.
-- Black's Law Dictionary
Legal Definition
Discharge; release; exoneration.
-- Ballentine's Law Dictionary