Definition of "cohesion"

For divers reasons, the capitalist class lacks this cohesion or solidarity, chief among which is the optimism bred of past success. And, again, the capitalist class is divided; it has within itself a class struggle of no mean proportions, which tends to irritate and harass it and to confuse the situation.

1905 April, Jack London, “(please specify the page)”, in War of the Classes, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd.

In general, it is neither advisable nor possible to create such maximally cohesive classes; on the other hand, we would like cohesion to be high. When cohesion is high, it means that the methods and variables of the class are co-dependent and hang together as a logical whole.

2009, Robert C. Martin, chapter 10, in Clean Code, Prentice Hall, page 140