overbore

adj

1. (not-comparable)Such that the capacity of the burning cartridge powder is greater than the volume within the barrel.

verb

1. (transitive)To modify so that the capacity of the burning cartridge powder is greater than the volume within the barrel.
2. To bore out more than is usual for the design; especially, to bore out to a degree that pushes the limit regarding the wall thickness of the casting.

   “The Model F engine was an overbored variation of the larger engine first applied to the Model D the previous year. This made it considerably oversquare: 5 inch bore (4.625 on the D) and 4.5 inch stroke displacing 353 cubic inches. It was rated 32.4 SAE horsepower, produced 35 at the same conditions and 40 maximum.”

3. (form-of, participle, past)simple past and past participle of overbear