Derogatory term for a plant, similar to a racial epithet.
A plant that aggressively colonizes disturbed habitats or places where it is not wanted.
Plant of disturbed habitats and perceived by the observer to be in the wrong place, like a dandelion, or a rose in a cabbage patch.
Any plant that is unwanted and a nuisance in the context of a particular environment, whether it be a garden, a cultivated field, a pasture or in natural woodland or forest. In natural vegetation weeds are almost by definition exotic to the region, but in gardens they may include some native plants. Weeds cause much economic loss and there is a large industry devoted to their control. They compete with cultivated plants for water, nutrients and sunlight as well as contaminating harvested crops, or spoiling the aesthetics of ornamental plantings.
Specialized, opportunistic plants that establish themselves in habitats disrupted by human activities. They are typically considered a nuisance.