Latin for "no contest." In a criminal proceeding, a defendant may enter a plea of nolo contendere, in which he does not accept or deny responsibility for the charges but agrees to accept punishment. The plea differs from a guilty plea because it cannot be used against the defendant in another cause of action. For example, pleading nolo contendere to criminal charges side steps possible estoppel claims from being filed in a civil lawsuit. Nolo contendere pleas differ from Alford pleas in this regard. See Alford plea.
Some states do not allow defendants to ask the court's permission to plead nolo contendere. In federal cases, the Rules of Federal Criminal Procedure allow such pleas, with the court's permission.
See, e.g. Keeney v. Tamayo-Reyes, 504 U.S. 1 (1992), Halbert v. Michigan, 545 U.S. 605 (2005).