Noun

(en-noun)

The act, process or ability of concentrating; the process of becoming concentrated, or the state of being concentrated.

# The direction of attention to a specific object.

# The act, process or product of reducing the volume of a liquid, as by evaporation.

# The act or process of removing the dress of ore and of reducing the valuable part to smaller compass, as by currents of air or water.

A field or course of study on which one focuses, especially as a student in a college or university.

The proportion of a substance in a whole.

* {{quote-magazine, year=2013, month=July-August, author= Philip J. Bushnell, magazine=(American Scientist)

, title= Solvents, Ethanol, Car Crashes & Tolerance , passage=Surprisingly, this analysis revealed that acute exposure to solvent vapors at concentrations below those associated with long-term effects appears to increase the risk of a fatal automobile accident. Furthermore, this increase in risk is comparable to the risk of death from leukemia after long-term exposure to benzene, another solvent, which has the well-known property of causing this type of cancer.}}

# (chemistry) The amount of solute in a solution measured in suitable units (e.g., parts per million (ppm))

The matching game pelmanism.

Noun

(en noun)

The situation or occurrence in which two or more objects or events act upon one another to produce a new effect; the effect resulting from such a situation or occurrence.

Be aware of interactions between different medications.

A conversation or exchange between people.

I enjoyed the interaction with a bunch of like-minded people.