Final answer:
Demographers refer to urban areas with at least 50,000 inhabitants as "urban areas" or "cities".
Step-by-step explanation:
Demographers refer to urban areas with at least 50,000 inhabitants as "urban areas" or sometimes as "cities". These areas are characterized by a higher population density and usually have a wide range of amenities and services available to residents. For example, New York City is an urban area with a much larger population than the minimum requirement of 50,000.