Reciprocal pronoun

A reciprocal pronoun is a pronoun that expresses mutual action or relationship. In English the reciprocal pronouns are each other and one another.

Some usage guides insist that each other should be used to refer to two people or things, and one another to more than two. As Bryan Garner has observed, "Careful writers will doubtless continue to observe the distinction, but no one else will notice" (Garner's Modern American Usage, 2009).

Examples of Reciprocal Pronouns:

"Leadership and learning are indispensable to each other."(John F. Kennedy, in a speech prepared for delivery on the day of his assassination, November 22, 1963)

"Men often hate each other because they fear each other; they fear each other because they don't know each other; they don't know each other because they can not communicate; they can not communicate because they are separated."

(Martin Luther King, Jr., Stride Toward Freedom: The Montgomery Story, 1958)

"All birds and animals talk to one another--they really have to, in order to get along."

(E.B. White, The Trumpet and the Swan. Harper & Row, 1970)

"The capacity of human beings to bore one another seems to be vastly greater than that of any other animal."

(H. L. Mencken, Notes on Democracy, 1926)

"There is no such thing as the State ,And no one exists alone;Hunger allows no choice ,To the citizen or the police;

We must love one another or die."(W.H. Auden, "September 1, 1939")

"People whose grandparents were all long-lived and lived with the family, shoot each other before they are 40."

(Robert Benchley, "How Long Can You Live?" The Benchley Roundup. Harper & Row, 1954)

"[W]ith a gasp of exasperation he rips away a great triangular piece [of the map] and tears the large remnant in half and, more calmly, lays these three pieces on top of each other and tears them in half, and then those six pieces and so on until he has a wad he can squeeze in his hand like a ball.

(John Updike, Rabbit, Run. Alfred A. Knopf, 1960)

"They all come together and Tohero introduces Margaret: 'Margaret Kosko, Harry Angstrom, my finest athlete, it's a pleasure for me to be able to introduce two such wonderful young people to one another.'"

(John Updike, Rabbit, Run. Alfred A. Knopf, 1960)

Usage Guide: Each Other or One Another?

"Each other and one another are known as the reciprocal pronouns. They serve either as determiners (in the possessive case) or as objects, referring to previously named nouns: Each other generally refers to two nouns; one another to three or more."

(Martha Kolln and Robert Funk, Understanding English Grammar. Allyn and Bacon, 1998)

"In modern English, most people normally use each other and one another in the same way. Perhaps one another is preferred (like one) when we are making very general statements, and not talking about particular people."

(Michael Swan, Practical English Usage. Oxford Univ. Press, 1995)

A Practical Grammar: In Which Words, Phrases, and Sentences Are Classified According to Their Offices, and Their Relation to Each Other.

(Title of a textbook by Stephen W. Clark, published by A. S. Barnes, 1853)

"Prescriptive style commentators have tried to insist that each other should be used between two people only, and one another when more than two were concerned. Yet Fowler (1926) spoke firmly against this distinction, arguing it had 'neither present utility nor a basis in historical usage.' His judgment is confirmed in citations recorded in the Oxford Dictionary (1989) and Webster's English Usage (1989)."

(Pam Peters, The Cambridge Guide to English Usage. Cambridge Univ. Press, 2004)