Edition
A numbered revision of a work, cited whenever it is not the first, because content and pagination differ between editions.
Cite the edition you actually used. A page reference to the 2nd edition will not land in the 3rd, and text may have been revised or cut. Styles abbreviate it: “2nd ed.” in APA and MLA, “2nd ed.” or “rev. ed.” in Chicago.
A reprint is not a new edition and needs no edition statement, though a reprint of an older work usually wants the original date recorded as well. A “revised edition” with no number takes the words rather than a numeral.