- any result occurring some time after its cause
- any delayed response to a stimulus or agent
Compare side effect
WordReference Random House Learner's Dictionary of American English © 2026
af•ter•ef•fect /ˈæftərɪˌfɛkt/USA pronunciation
n. [countable]
WordReference Random House Unabridged Dictionary of American English © 2026- a delayed effect, as one that follows the stimulus that produced it:the aftereffects of the drug.
af•ter•ef•fect
(af′tər i fekt′, äf′-),USA pronunciation n.
- a delayed effect;
an effect that follows at some interval after the stimulus that produces it. - Medicinea result appearing after the first effect due to an agent, usually a drug, has gone.
- after + effect 1810–20
Collins Concise English Dictionary © HarperCollins Publishers::
aftereffect /ˈɑːftərɪˌfɛkt/ n
'aftereffects' also found in these entries (note: many are not synonyms or translations):