repetition of messages to reduce the probability of errors in transmission
"The satellite system employs signal redundancy by repeating each message three times to minimize data loss during transmission."
the attribute of being superfluous and unneeded
"the use of industrial robots created redundancy among workers"
(electronics) a system design that duplicates components to provide alternatives in case one component fails
"The server room employs redundancy by installing duplicate power supplies and cooling units so that the network remains online even if a single piece of hardware malfunctions."
repetition of an act needlessly
"The manager's insistence on reviewing the same report three times was pure redundancy."
The state of being redundant
"The redundancy in the factory's staffing meant that many workers were laid off after automation was introduced."
In plain English: Redundancy is when something repeats itself unnecessarily so that if it fails, there's still another copy to take its place.
"The company is implementing redundancy measures to save money by laying off several employees."
The word redundancy comes from the Latin redundare, which originally meant to overflow or run over. It entered English through French and eventually took on its modern sense of superfluousness.