Definition

each of two or more in reciprocal action or relation //looked at each other in surprise

each other vs. one another

Some handbooks and textbooks recommend that each other be restricted to reference to two and one another to reference to three or more. The distinction, while neat, is not observed in actual usage. Each other and one another are used interchangeably by good writers and have been since at least the 16th century.

First Known Use

before 12th century, in the meaning defined above