1. A group of words arranged according to grammatical rules that communicate with a statement, or with questions, demands, with wishes, etc.: In written English, the first word of a sentence is capitalized and the sentence ends with a period, a question mark, or an exclamation point.

Sentences usually have subjects and verbs and should be constructed to form complete sentences

2. A punishment given to someone who has been convicted of breaking the law as indicated by a legal court: The sentence of the first offender for possession of drugs was five years in prison.
3. Etymology: from a Latin ancestor sententia, which originally meant "feeling" because it was a derivative of sentire, "to feel".

Later, it expanded to mean "an opinion, a judgment"; which developed into the use of English sentence, meaning "judicial declaration of punishment".

To officiously state what the punishment will be for someone by a court of law: The defendant was sentenced by the judge to ten years in prison for armed robbery.