Redundancy

(plural redundancies)

The state of being redundant; a superfluity; something redundant or excessive; a needless repetition in language; excessive wordiness.
Duplication of components or circuits to provide survival of the total system in case of failure of single components.

2006, Lauren Bean, Richard E. Friedman, Chapter 5: School Safety in the Twenty First Century: Adapting to New Security Challenges Post-9/11, James J. F. Forest (editor), Homeland Security: Protecting Americaâ€²s Targets, Volume 2: Public Spaces and Social Institutions, redundancies%22+staff+-intitle:%22redundancy%22+-inauthor:%22%22&hl=en&sa=X&ei=wBYAUMywFI-jiAfvrKCOCA&redir_esc=y#v=onepage&q=%22redundancy%22|redundancies%22%20staff%20-intitle%3A%22redundancy%22%20-inauthor%3A%22%22&f=false page 108,Staff redundancy is needed in the event that a supervisor and key unit supervisors are not present or unable to act in an emergency.

Duplication of parts of a message to guard against transmission errors.
(chiefly UK, Australia, New Zealand) The state of being unemployed because one's job is no longer necessary; the dismissal of such an employee; a layoff.

1981, New Zealand House of Representatives. Parliamentary Debates, Volume 442, redundancies%22+staff+-intitle:%22redundancy%22+-inauthor:%22%22&dq=%22redundancy%22|redundancies%22+staff+-intitle:%22redundancy%22+-inauthor:%22%22&hl=en&sa=X&ei=wBYAUMywFI-jiAfvrKCOCA&redir_esc=y page 4212,Has he received any representation from Air New Zealand management about redundancy proposals for Air New Zealand staff; and, if so, do these proposals include redundancy agreements?
1983, UK House of Commons, Papers by Command, Volume 40, redundancies%22+staff+-intitle:%22redundancy%22+-inauthor:%22%22&dq=%22redundancy%22|redundancies%22+staff+-intitle:%22redundancy%22+-inauthor:%22%22&hl=en&sa=X&ei=wBYAUMywFI-jiAfvrKCOCA&redir_esc=y page lvi,The potential savings did not take into account once-and-for-all staff redundancy costs of Â£16.5 million and unspecified costs involved in increasing stock levels....
2003, K. Brendow, Restructuring Estoniaâ€²s Oil Shale Industry: What Lessons from the Restructuring the Coal Industries in Central and Eastern Europe?, Oil Shale (journal), redundancies%22+staff+-intitle:%22redundancy%22+-inauthor:%22%22&hl=en&sa=X&ei=wBYAUMywFI-jiAfvrKCOCA&redir_esc=y#v=onepage&q&f=false page 307,In Estonia, in addition, the ethnical aspects of staff redundancy programmes have to be taken into account.

(legal) surplusage inserted in a pleading which may be rejected by the court without impairing the validity of what remains.

(state of being redundant) redundance rare, pro-chrono continuum rare, superfluity, superfluousness
(thing that is redundant) dead wood, superfluity
(duplication in case of failure)
(duplication in case of transmission error)
(state of being unemployed) retirement
(instance or act of dismissal) sacking
(surplus remarks on a plea)