crisis
a crucial stage or turning point in the course of something
social
living together or enjoying life in communities or organized groups
worldwide
spanning or extending throughout the entire world
depression
a sunken or depressed geological formation
nuclear
constituting or like a nucleus
eavesdrop
listen without the speaker's knowledge
citadel
a stronghold into which people could go for shelter during a battle
segregation
the act of segregating or sequestering
Ellis Island
an island in New York Bay that was formerly the principal immigration station for the United States
polio
an acute viral disease marked by inflammation of nerve cells of the brain stem and spinal cord
vaccine
immunogen consisting of a suspension of weakened or dead pathogenic cells injected in order to stimulate the production of antibodies
passage
the act of passing from one state or place to the next
moon shot
the launching of a spacecraft to the moon
challenge
a call to engage in a contest or fight
Middle East
the area around the eastern Mediterranean; from Turkey to northern Africa and eastward to Iran; the site of such ancient civilizations as Phoenicia and Babylon and Egypt and the birthplace of Judaism and Christianity and Islam; had continuous economic and political turmoil in the 20th century
generation
group of genetically related organisms constituting a single step in the line of descent
