Definition - A set of words that expresses a statement, exclamation, question, or command, and which contains (or implies) a subject and a predicate.

1. Traditional grammarians claim that there are three types:
(1) simple sentences (one main clause)
(2) complex sentences (one or more subordinate clauses)
(3) compound sentences (two or more independent clauses)

Example -
This is a simple sentence.

Etymology -
The word derives via Old French from the Latin sententia, thought or opinion.

Oxford English Dictionary -
The first citation for the word in this sense is from 1447:
"Fro sentence to sentence, I dar wele seyn, I hym haue folwyde euen by & by."
( O. Bokenham Seyntys, Agnes 682)

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