Redundancy.

It's a strange word.  Usually in Engineering terms it's a good thing... Redundancy of systems generally means that you have two (or in some cases more) parallel systems that are capable of carrying out the same function, meaning that you can cope with complete failure of one system and have the process in question continue.

Aircraft are a good example of this.  Most commercial airliners have three, or sometimes four independent hydraulic systems for moving control surfaces.  You can hence lose complete systems (be that through fluid loss, pump failure or some other catastrophic fault) and the aircraft as a whole still be flyable.  It's even theoretically possible now with computer control of engine thrust for the entire hydraulics system to be redundant, as after lessons learned where a few airliners have lost all of their hydraulic systems, basic flight control can still be maintained, certainly enough to get the aircraft on the ground at least.

However, when referring to people, or in particular, job roles, the word has a slighly more unpleasant meaning:  The job role is no longer needed and by inference, the person is no longer needed.  It's a shitty situation to find yourself in and leads to a significant increase in uncertainty for the future.  Now, don't get me wrong; the future is not certain in the first place.  Risk exists in all aspects of our lives.  A common statement being "you could be hit by a bus tomorrow".  Equally you could be squashed by an airliner falling from the sky, possibly due to the failure of all it's redundant systems.  However, announcement of personal redundancy really does make the future very much unknown and leaves people feeling very vulnerable.

 It's happened to me once before.  That time was of no real issue, as I had every intention of leaving the company in question anyway, had no responsibilities, no financial ties and quite frankly could not care less.  I was somewhat frustrated not to have worked for the company long enough to qualify for a decent settlement, but nevertheless it didn't really affect me.

This one will.