Behavior reflex can be defined as an automatic or innate response by an individual to a particular situation or stimulus. There are a number of synonyms that can be used to describe behavior reflex including instinct, involuntary action, innate behavior, reflexive response and automatic reaction. Other terms that can be used to describe behavior reflex include knee-jerk response, unthinking action, reflex action, mechanical reaction, and spontaneous behavior. These terms all refer to the immediate and automatic ways in which people or animals react to stimuli, whether they are conscious of their reactions or not. Having a good understanding of these synonyms can enable one to communicate more effectively about this important aspect of human and animal behavior.