The constituent of a photographic developer that speeds up development rate. Also known as activator.

1. Any substance added to stucco, plaster, mortar, concrete, cement, and so on to hasten the set.

2. In the vulcanization process, a substance, added with a curing agent, to speed processing and enhance physical characteristics of a vulcanized material.

A device for varying the speed of an automotive vehicle by varying the supply of fuel.

See <<particle accelerator>>