Redundancy

noun

1. The state of being redundant
2. A superfluity; something redundant or excessive; a needless repetition in language
3. Duplication of components or circuits to provide survival of the total system in case of failure of single components.
4. Duplication of parts of a message to guard against transmission errors.
5. The state of being unemployed because one's job is no longer necessary; the dismissal of such an employee; a layoff.