one of the marks used to indicate the beginning and end of a quotation, in English usually shown as “ at the beginning and ” at the end, or, for a quotation within a quotation, of single marks of this kind, as “He said, "I will go.' ” Frequently, esp. in Great Britain, single marks are used instead of double, the latter being then used for a quotation within a quotation. Also,quote' mark".
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.