Alright I give.
This is probably a better definition of the origin. From what I learned by observations over the evolution of this whole thing from the 80's ... a shard is a part of a whole, the whole being the cluster, and a shard being a single computation unit as I said before. Apparently it's more popularly used for databsae, where the database is split between multiple computational points, which is closer to my definition( So for isntance eve would be 'sharded' even though it's one server, or Elite dangerous... or Second Life....) ... but apparently it has other origins that end up regarding the server as a whole....
from http://forums.riftgame.com/general-discussions/general-discussion/40451-why-servers-called-shards.html
Why are the servers called "shards"?