It is also called alien life, or, if it is a sentient and/or relatively complex individual, an extraterrestrial or alien (or, to avoid confusion with the legal sense of alien , a  space alien ).lthough many scientists expect extraterrestrial life to exist, so far no unambiguous evidence for its existence exists. The science of extraterrestrial life is known as exobiology. The science of astrobiology also considers life on Earth as well, and in the broader astronomical context.
repression - (psychiatry) the classical defense mechanism that protects you from impulses or ideas that would cause anxiety by preventing them from becoming conscious. psychiatry, psychological medicine, psychopathology-the branch of medicine dealing with the diagnosis and treatment of mental disorders.
Collective security - Collective defense. 1  Collective defense is an arrangement, usually formalized by a treaty and an organization, among participant states that commit support in defense of a member state if it is attacked by another state outside the organization.