What makes a plant a weed?

Answer 1

What makes a weed a weed is that a weed is an unplanned plant such as a dandelion. Even a useful plant is a weed if it comes up in the wrong place but most weeds are plants that have no use to humans and interfere in some way with human intentions.

Answer 2

A weed is any plant that is growing in a place that it is not wanted. Even beneficial plants can be weeds. A couple of examples are mint and basil. They can spread to areas where they are not wanted and become pests (weeds).