The use of “attenuate” in medicine is not new. In the 16th century, eating dried figs was claimed to attenuate the body fluids.

Now “attenuate” refers to procedures that weaken an agent of disease (a pathogen). An attenuated virus is a weakened, less vigorous virus. A vaccine against a viral disease can be made from an attenuated, less virulent strain of the virus, a virus capable of stimulating an immune response and creating immunity but not causing illness.

The word “attenuate” derives from a combination of the Latin prefix “ad-” meaning “to” or “toward” and “tenuis” meaning “thin.”

To reduce in force, value, amount, or degree; weaken: Medicine attenuated the fever’s effect.

To lessen the density of; rarefy.

Biology. To make (bacteria or viruses) less virulent.

Electronics. To reduce (the amplitude of an electrical signal) with little or no distortion.

Pronunciation: \ə-ˈten-yə-wət, -yü-ət\

Function: adjective

Etymology: Middle English attenuat, from Latin attenuatus, past participle of attenuare to make thin, from ad- + tenuis thin — more at thin

Date: 15th century

1 : reduced especially in thickness, density, or force

2 : tapering gradually usually to a long slender point