| Term | Definition |
| behavior | way an organism reacts to changes in its internal or external environment |
| stimulus | signal to which an organism responds |
| response | single, specific reaction to a stimulus |
| innate behavior | instinct, or inborn behavior; appears in fully functional form the first time it is performed |
| learning | alterations in behavior as a result of experience; acquired behavior |
| habituation | when an animal decreases or stops its response to a repetitive stimulus that neither rewards or harms it |
| classical conditioning | when an animal makes a mental connection betwen a stimulus and some kind or reward or punishment |
| operant conditioning | when an animal learns to behave in a certain way through repeated practice; trial-and-error learning |
| insight learning | reasoning; when an animal applies something it has already learned to a new situation without a period of trial and error |
| imprinting | learning based on early experience; once it has occurred, it cannot be changed |
| migration | periodic movement and return of animals from one place to another |
| circadian rhythm | behavioral cycle that occurs in a daily pattern |
| courtship | when an animal sends out stimuli in order to attract a member of the opposite sex |
| territory | specific area occupied and protected by an animal or group of animals |
| aggression | threatening behavior that one animal uses to gain control over another |
| communication | passing of information from one organism to another |
| language | system of communication that combines sounds, symbols, or gestures according to a set of rules |