Nanometer - A unit of length equal to one one-billionth (1 x 10-9) of a meter.⏎
Natural Selection - The process by which certain heritable traits that contribute to the survival and reproductive success of an organism become more widespread within a population over successive generations.⏎
Nerve Toxin - Also called neurotoxins, these refer to poisonous substances that cause damage to cells in the nervous system.⏎
Outbreak - An unexpected increase in the incidence of a particular disease over a given time period and geographic range. A general term that may refer either to an epidemic or a pandemic.⏎