side effect
or side-ef·fect
noun
any effect of a drug, chemical, or other medicine that is in addition to its intended effect, especially an effect that is harmful or unpleasant.
any accompanying or consequential and usually detrimental effect: the side effects of air pollution.
Origin of side effect
First recorded in 1880–85
Words nearby side effect
side circuit,
side curl,
side deal,
side dish,
side drum,
side effect,
side horse,
side meat,
side money,
side of the tracks,
side pot
British Dictionary definitions for side effect
side effect
noun
any unwanted nontherapeutic effect caused by a drug
Compare aftereffect (def. 2)
any secondary effect, esp an undesirable one
Medical definitions for side effect
side effect
n.
A peripheral or secondary effect, especially an undesirable secondary effect of a drug or therapeutic regimen.