affect

The word affect is both a verb and a noun, though it is best known in its verb form, where it can be thought of as meaning to influence or cause a change or produce an effect on someone or something. It is pronounced with a short a (ə-‘fekt).

Examples of use:

• The bright light affected him greatly, causing a migraine.
• Fruits and vegetables affect health in so many positive ways.
• It is a disease that affects millions of patients each year.
• Diabetes is a disease that affects the pancreas.
• Visiting the art exhibit was an experience that affected them powerfully.
• Try not to let emotions affect your decision.

As a noun, affect can be thought of as describing emotion. It is pronounced with emphasis on the a. (ˈa-ˌfekt, from the German Affekt, borrowed from Latin affectus).

Use this noun carefully, as it can be confusing to readers and is often used in a psychological or clinical manner. Examples:

• The psychological notes describe a flat affect of the patient, but an excitable vocal reaction.
• Apathy is often accompanied by a notable reduction in facial affect.
• She is an upbeat person and reflects that in her characteristic chipper affect.

If, as a noun, affect creates confusion in the sentence, reword the sentence or use a synonym.

The words affect and effect are not interchangeable. For more on how to use effect as either a noun or a verb, see effect.