redundancy

Concise Oxford English Dictionary © 2008 Oxford University Press:
redundant/rɪˈdʌndənt/

▶adjective

• 1 no longer needed or useful; superfluous.

  ■ (of words) able to be omitted without loss of meaning or function.

  ■ Engineering (of a component) not strictly necessary but included in case another component fails.

• 2 Brit. (of a person) no longer employed because there is no more work available.

– derivatives
redundancy noun (pl. redundancies),
redundantly adverb.

– origin C16 (in the sense ‘abundant’): from L. redundant-, redundare (see redound).