Cohesion

The mutual attraction of soil particles due to molecular and capillary forces in the presence of water. Cohesion is high in clay (especially dry) but of little significance in silt or sand. The ability of a substance to stick to itself and pull itself together. Molecular attraction which holds two particles together.

The extent to which a component performs a single well-defined task. A strongly cohesive method, for instance, will perform a single task, such as adding an item to a data structure, or sorting some data, whereas a weakly cohesive method will be responsible for several disparate tasks. Weakly cohesive components should, in general, be split into separate more cohesive components. The java.util package is a weakly cohesive package because it contains many unrelated classes and interfaces, whereas the java.io package is highly cohesive.