curb is the sidewalk edge, which marks the gap between the pedestrian sidewalk and the pavement where cars pass.
It is a construction usually formed by a row of concrete blocks or stones. Brazilian traffic legislation also calls for a sidewalk guide.
There is no official origin for the term, but there are hints at the origin of streets in modern cities. Previously, the streets had a central path, a channel where the water flowed. Whereupon modern urbanization has created the concept of a street with a slight inclination from the center, making that that single central stream of water was distributed into two lateral streams, forming on each side a curb.
Today the streets still have constructions called gutters, which are next to the curb, and serve to drain the dammed water.
The plural of curb is curbs.
Some synonyms for curb: guide, curb or curb.
In civil construction, it is also called the leveling on the top of a concrete wall so that it fits another construction. Or even the angle formed in the door frame.
In shipbuilding, it is a bulkhead in the ship's hold used to balance cargo.
Curb or Curb
Both forms exist in the Portuguese language, with different meanings.
When we want to talk about the sidewalk edge, the correct one is curb, with a hyphen.
The separate curb means half a thread.
As in the examples:
"I went to make the goal and scraped the wheel of the car on the curb"
and
"I need a curb of string to finish the package."