redundancy in WordNet English dictionary

1. the attribute of being superfluous and unneeded
   "the use of industrial robots created redundancy among workers"
   redundancy  redundance 
   
2. repetition of an act needlessly
   redundancy 
   
3. (electronics) a system design that duplicates components to provide alternatives in case one component fails
   redundancy 
   
4. repetition of messages to reduce the probability of errors in transmission
   redundancy