What is the meaning of Priming?

The implicit memory effect in which exposure to a stimulus influences response to a subsequent stimulus.

A substance used as a primer.

The powder or other combustible used to communicate fire to a charge of gunpowder, as in a firearm.

The carrying over of water, with the steam, from the boiler, as into the cylinder.

present participle and gerund of prime

Source: wiktionary.org