A. People moving from rural areas to urban areas B. The growth in the population of urban areas as a result of several factors C. The increase in the proportion of people living in urban areas D. People moving from urban areas to rural areas
Urbanism is best defined as “the increase in the proportion of people living in urban areas”. The actual definition, courtesy of Merriam-Webster’s online dictionary, is “the characteristic way of living of those in cities”. Urbanism refers more to how people live than the places that they live in. However, some do use ‘urbanism’ to refer to where people live. It also depends on the context of what is said when the word is used.
That said, this word was first used in 1884, when cities started to become a thing. It was used to refer to the definition asked for by this question, the increase in people in the urban areas. In this context, it was meant to be a way to resist change.