Real Dictionary

sentence
countable noun: A sentence is a group of words which, when they are written down, begin with a capital letter and end with a full stop, question mark, or exclamation mark. Most sentences contain a subject and a verb.
variable noun: In a law court, a sentence is the punishment that a person receives after they have been found guilty of a crime.
verb: When a judge sentences someone, he or she states in court what their punishment will be.

sentence in American English
a decision or judgment, as of a court; esp., the determination by a court of the punishment of a convicted person
to pronounce judgment or punishment upon (a convicted person); condemn (to a specified punishment)
noun: a grammatical unit of one or more words, bearing minimal syntactic relation to the words that precede or follow it, often preceded and followed in speech by pauses, having one of a small number of characteristic intonation patterns, and typically expressi

sentence in British English
noun: a sequence of words capable of standing alone to make an assertion, ask a question, or give a command, usually consisting of a subject and a predicate containing a finite verb
verb: to pronounce sentence on (a convicted person) in a court of law