Either of a pair of punctuation marks used primarily to mark the beginning and end of a passage attributed to another and repeated word for word, but also to indicate meanings or glosses and to indicate the unusual or dubious status of a word. They appear in the form of double quotation marks (" ”) and single quotation marks (' '). Single quotation marks are usually reserved for setting off a quotation within another quotation.
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.