An adverse physiological response to a substance that has been breathed in, ingested, or touched
An action performed or a feeling experienced in response to a situation or event
A person's ability to respond physically and mentally to external stimuli
A chemical process in which two or more substances act mutually on each other and are changed into different substances, or one substance changes into two or more other substances
the act of reacting (to respond to a stimulus) [n REACTIONS]
An analogous transformation of atomic nuclei or other particles
A mode of thinking or behaving that is deliberately different from previous modes of thought and behavior
Opposition to political or social progress or reform
Repulsion or resistance exerted in opposition to the impact or pressure of another body; a force equal and opposite to the force giving rise to it