The Collaborative International Dictionary of English v.0.48:
Concentrator \Con"cen*tra`tor\, n. (Mining)
1. An apparatus for the separation of dry comminuted ore, by
exposing it to intermittent puffs of air. --Knight.
2. (Firearms) A frame or ring of wire or hard paper fitting
into the cartridge case used in some shotguns, and holding
the shot together when discharged, to secure close
shooting; also, a device for slightly narrowing the bore
at the muzzle for the same purpose.
[Webster 1913 Suppl.] Concentric
The Free On-line Dictionary of Computing (30 December 2018):
A device that combines the data streams from
many simultaneously active inputs into one shared channel in
such a way that the streams can be separated after
transmission. The concentrator's output bandwidth must be at
least as great as the total bandwidth of all simultaneously
active inputs. A concentrator is one kind of multiplexing
For example, a concentrator may be used to connect 24 2400 bps
TTYs to a host via a 57600 bps channel.