Diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

the movement of molecules and ions from a high concentration area to a lower concentration area down the concentration gradient as a result of their random movement

Moving Venmo balance from one account to another back and forth until all of you have the same balance and no one wants to put their card down anymore.

A modified down tube for a water pipe that instead of just having one large hole opening into the water, instead the glass comes to a closed tip, along which are several smaller holes. This supposedly cools the smoke before being inhaled by diffusing (spreading) the smoke over a larger area.

If something is diffuse, it is very spread out or scattered.

transitive verb
1a : to pour out and permit or cause to spread freely b : extend, scatter c : to spread thinly or wastefully

2: to subject to diffusion; especially : to break up and distribute (incident light) by reflection

intransitive verb
1: to spread out or become transmitted especially by contact

2: to undergo diffusion

A piece of automotive bodywork that is meant to deliver downforce by channeling air under the car, especially under the midsection and rear, so that it creates a low-pressure system under the car which sucks the vehicle to the ground. This increases traction and stability at high speeds.

These are especially prevalent on high-performance sports cars, supercars and most racing cars when putting spoilers that create similar downforce would just cause too much drag.