redundant

Etymology

From Latin redundāns, present participle of redundō (“to overflow, redound”), from red- (“again, back”) + undō (“to surge, flood”), from unda (“a wave”).

adj

1. Superfluous; exceeding what is necessary, no longer needed.
   In the living state, the body is observed to receive aliment; to assimilate a part; to evacuate what is redundant or useless; … 1822, John Barclay, chapter I, in An Inquiry Into the Opinions, Ancient and Modern, Concerning Life and Organization, Edinburgh, London: Bell & Bradfute; Waugh & Innes; G. & W. B. Whittaker, section I, page 1
   A key driver has been the approval of a new housing and employment development called Fawley Waterside, with 1,500 homes planned on the site of a redundant power station on the edge of Southampton Water. December 16 2020, “Network News: "Robust case" for Fawley branch reopening”, in Rail, page 14
   Two entrants shared this award for their work on two quite different stations, but with the same purpose of bringing a redundant station building back into use for the benefit of the community, with the added result of conserving an historic building. December 15 2021, Robin Leleux, “Awards honour the best restoration projects: The Network Rail Community Award: Saltash and Stow”, in RAIL, number 946, page 58
2. (of words, writing, etc) Repetitive or needlessly wordy.
3. (chiefly Britain, Ireland, New Zealand, Australia) Dismissed from employment because no longer needed.
   Four employees were made redundant.
4. Duplicating or able to duplicate the function of another component of a system, providing backup in the event the other component fails.
   The two lines are mainly used for redundant and therefore fault-tolerant message transmission, but they can also transmit different messages. 2013, Tom Denton, Automobile Electrical and Electronic Systems, page 142