Definition:
"Concrete jungle" is a noun that describes a part of a city filled with big, modern buildings made of concrete (a strong material used in construction). It often refers to areas that feel crowded, uninviting, and sometimes dangerous or unpleasant.
In more advanced contexts, "concrete jungle" can also be used metaphorically to describe any environment that feels harsh, competitive, or lacking in warmth and natural beauty, not just city areas.
"Concrete jungle" paints a picture of modern urban life that can often feel overwhelming and harsh.