redundant

/rɪˈdʌndənt/
adjective
  1. Not or no longer needed or useful; superfluous.
    • Her explanation was redundant because everyone already understood the topic.
    • The factory laid off several workers whose jobs were made redundant by automation.
    • The old computer system became redundant after the upgrade.
  2. (of words or writing) Using more words than necessary; repetitive.
    • His speech was full of redundant phrases that bored the audience.
    • The phrase 'free gift' is redundant because a gift is always free.
    • Good editing removes redundant words to make writing clearer.
  3. (of a system or component) Designed to have a duplicate or backup in case of failure.
    • The spacecraft's navigation system is redundant to prevent mission failure.
    • The airplane has redundant engines so it can fly safely if one fails.
    • A redundant power supply ensures the server stays on during an outage.