An ELT Glossary : Reciprocal pronouns

Reciprocal pronouns are those which indicate a mutual exchange between the two or more subjects of the verb. In English this is indicated by the pronouns each other and one another. For example:

John and Karen looked at each other /John and Karen looked at one another.

indicates that John looked at Karen and Karen looked at John.

Both these pronouns can also be used in the possessive :

The group collaborated by checking each other's work. / The group collaborated by checking one another's work.

- ie each member of the group checked the work of at least one of the others