naming explosion A sudden increase in an infant’s vocabulary, especially in the number of nouns, that begins at about 18 months of age.

National Assessment of Educational Progress (NAEP) An ongoing and nationally representative measure of U.S. children’s achievement in reading, mathematics, and other subjects over time; nicknamed “the Nation’s Report Card.”

naturally occurring retirement community (NORC) A neighborhood or apartment complex whose population is mostly retired people who moved to the location as younger adults and never left.

nature A general term for the traits, capacities, and limitations that each individual inherits genetically from his or her parents at the moment of conception.

neglectful/uninvolved parenting An approach to child rearing in which the parents are indifferent toward their children and unaware of what is going on in their children’s lives.

neurocognitivedisorders (NCDs) Impairments of intellectual functioning caused by organic brain damage or disease. NCDs may be diagnosed as major or mild, depending on the severity of symptoms. They become more common with age, but they are abnormal and pathological even in the very old.

neuron One of billions of nerve cells in the central nervous system, especially in the brain.

neurotransmitter A brain chemical that carries information from the axon of a sending neuron to the dendrites of a receiving neuron.

No Child Left Behind (NCLB) Act A U.S. law enacted in 2001 that was intended to increase accountability in education by requiring states to qualify for federal educational funding by administering standardized tests to measure school achievement.

norm An average, or standard, measurement, calculated from the measurements of many individuals within a specific group or population.

nuclear family A family that consists of a father, a mother, and their biological children under age 18.

nurture A general term for all the environmental influences that affect development after an individual is conceived.