As far as I know, it is the seating of bearing on a shaft or housing collar (that is called the abutment surface in bearing terminology), but what you mean- or from whatever literature you have seen it- may be context specific and that will not be proper to guess.
__________________
Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
well, the abutment is the strong structure the bearing sits in that makes it stay in one place under the forces the armature creates under power, also called the bearing housing.
If you have a 1000 HP motor. that delivers enough power to move 550,000 pounds up at the rate of one foot per second. So if this is a mine hoist lifting 300 tons or so, the abutments must be capable taking this force without breaking.
In a bicycle, when you pedal, the lower bracket abutments that hold the bearings hold them in place as you pedal the bike
Abutment for Bearings 
Re: Abutment For Bearings
