A weed is a plant that people think is bad, because it is growing in the wrong place. Only smaller plants are often called weeds.[1]
A person may grow a plant because it has beautiful flowers, but other people may think that this plant is a weed for some reason. This may be for one of these reasons:
If someone is farming a plant and it then moves outside the farm, the plant may then be called a weed.
Some plants are very hard to stop once they start growing. These are called invasive weeds.
Weed is also a name for any wild plant, one that people do not use for anything.