software rot - Computer Definition
The gradual decline in performance of an application in the computer. Software rot may manifest as slow execution or erratic behavior. Also called "software erosion," "bit rot" and "code rot," it generally occurs for two reasons. The first is bad software design in which the program's own configuration files can become corrupted after extended use. Deleting such files or re-installing the app may solve the problem. The second reason is incompatibility with the environment. Occasionally, a new version of the operating system can cause existing applications to fail or degrade, in which case upgrading the app, if possible, is typically the only solution.